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  • 1. Ahlström, Christer
    et al.
    Anund, Anna
    Fors, Carina
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Effects of the road environment on the development of driver sleepiness in young male drivers2018In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 112, p. 127-134Article in journal (Refereed)
    Abstract [en]

    Latent driver sleepiness may in some cases be masked by for example social interaction, stress and physical activity. This short-term modulation of sleepiness may also result from environmental factors, such as when driving in stimulating environments. The aim of this study is to compare two road environments and investigate how they affect driver sleepiness. Thirty young male drivers participated in a driving simulator experiment where they drove two scenarios: a rural environment with winding roads and low traffic density, and a suburban road with higher traffic density and a more built-up roadside environment. The driving task was essentially the same in both scenarios, i.e. to stay on the road, without much interaction with other road users. A 2 x 2 design, with the conditions rural versus suburban, and daytime (full sleep) versus night-time (sleep deprived), was used. The results show that there were only minor effects of the road environment on subjective and physiological indicators of sleepiness. In contrast, there was an increase in subjective sleepiness, longer blink durations and increased EEG alpha content, both due to time on task and to night-time driving. The two road environments differed both in terms of the demand on driver action and of visual load, and the results indicate that action demand is the more important of the two factors. The notion that driver fatigue should be countered in a more stimulating visual environment such as in the city is thus more likely due to increased task demand rather than to a richer visual scenery. This should be investigated in further studies.

  • 2. Ahlström, Christer
    et al.
    Anund, Anna
    Fors, Carina
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    The effect of daylight versus darkness on driver sleepiness: a driving simulator study2018In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27, no 3, article id e12642Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness studies are often carried out with alert drivers during daytime and sleep-deprived drivers during night-time. This design results in a mixture of different factors (e.g. circadian effects, homeostatic effects, light conditions) that may confound the results. The aim of this study was to investigate the effect of light conditions on driver sleepiness. Thirty young male drivers (23.6 ± 1.7 years old) participated in a driving simulator experiment where they drove on a rural road. A 2 × 2 design was used with the conditions daylight versus darkness, and daytime (full sleep) versus night-time (sleep deprived). The results show that light condition had an independent effect on the sleepiness variables. The subjective sleepiness measured by Karolinska Sleepiness Scale was higher, lateral position more left-oriented, speed lower, electroencephalogram alpha and theta higher, and blink durations were longer during darkness. The number of line crossings did not change significantly with light condition. The day/night condition had profound effects on most sleepiness indicators while controlling for light condition. The number of line crossings was higher during night driving, Karolinska Sleepiness Scale was higher, blink durations were longer and speed was lower. There were no significant interactions, indicating that light conditions have an additive effect on sleepiness. In conclusion, Karolinska Sleepiness Scale and blink durations increase primarily with sleep deprivation, but also as an effect of darkness. Line crossings are mainly driven by the need for sleep and the reduced alertness at the circadian nadir. Lane position is, however, more determined by light conditions than by sleepiness.

  • 3. Ahlström, Christer
    et al.
    Nyström, Marcus
    Holmqvist, Kenneth
    Fors, Carina
    Sandberg, David
    Anund, Anna
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fit-for-duty test for estimation of drivers' sleepiness level: Eye movements improve the sleep/wake predictor2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 26, p. 20-32Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a driver’s sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS ⩾ 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.

  • 4. Ahlström, Christer
    et al.
    Solis-Marcos, Ignacio
    Nilsson, Emma
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    The impact of driver sleepiness on fixation-related brain potentials2020In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 29, no 5, article id e12962Article in journal (Refereed)
    Abstract [en]

    The effects of driver sleepiness are often quantified as deteriorated driving performance, increased blink durations and high levels of subjective sleepiness. Driver sleepiness has also been associated with increasing levels of electroencephalogram (EEG) power, especially in the alpha range. The present exploratory study investigated a new measure of driver sleepiness, the EEG fixation-related lambda response. Thirty young male drivers (23.6 +/- 1.7 years old) participated in a driving simulator experiment in which they drove on rural and suburban roads in simulated daylight versus darkness during both the daytime (full sleep) and night-time (sleep deprived). The results show lower lambda responses during night driving and with longer time on task, indicating that sleep deprivation and time on task cause a general decrement in cortical responsiveness to incoming visual stimuli. Levels of subjective sleepiness and line crossings were higher under the same conditions. Furthermore, results of a linear mixed-effects model showed that low lambda responses are associated with high subjective sleepiness and more line crossings. We suggest that the fixation-related lambda response can be used to investigate driving impairment induced by sleep deprivation while driving and that, after further refinement, it may be useful as an objective measure of driver sleepiness.

  • 5.
    Andreasson, Anna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Karshikoff, Bianka
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Lidberg, Lisa
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Ingvar, Martin
    Hoglund, Caroline Olgart
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    The effect of a transient immune activation on subjective health perception in two placebo controlled randomised experiments2019In: PLOS ONE, E-ISSN 1932-6203, Vol. 14, no 3, article id e0212313Article in journal (Refereed)
    Abstract [en]

    Background Patient-reported outcomes predict mortality and play increasingly important roles in care, but factors that modify central measures such as health ratings have been little investigated. Building on designated immune-to-brain pathways, we aimed to determine how a short-term induced inflammation response impacts self-reported health status. Methods Lipopolysaccharide injections were used to provoke acute systemic inflammatory responses in healthy men and women and were compared to placebo in two double-blind randomized experiments. In Experiment 1, 8 individuals (mean 24 years; SD = 3.7) received lipopolysaccharide 0.8 ng/kg once and placebo once in a cross-over design, and in Experiment 2, 52 individuals received either lipopolysaccharide 0.6 ng/kg or placebo once (28.6 years; SD = 7.1). Main outcomes were perceived health (general and current), sickness behaviour (like fatigue, pain and negative affect), and plasma interleukin-6, interleukin-8 and tumour necrosis factor-alpha, before and after injection. Results Compared to placebo, lipopolysaccharide lead to a deterioration in both self-rated general (Experiment 1, b = 1.88 for 0.8 ng/kg) and current health (Experiment 1 b = -3.00; and Experiment 2 b = -1.79) 1.5h after injection (p's<0.01), effects that remained after 4.5 to 5 hours (p's<0.05). The effect on current health in Experiment 2 was mediated by increased inflammation and sickness behaviour in response to lipopolysaccharide injection (beta = -0.28, p = 0.01). Conclusion Health is drastically re-evaluated during inflammatory activation. The findings are consistent with notions that inflammation forms part of health-relevant interoceptive computations of bodily state, and hint at one mechanism as to why subjective health predicts longevity.

  • 6.
    Andreasson, Anna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden; Macquarie University, Australia.
    Schiller, Helena
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Berntson, Erik
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Work and organizational psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Brief report: Contemplate your symptoms and re-evaluate your health. A study on working adults2019In: Journal of Health Psychology, ISSN 1359-1053, E-ISSN 1461-7277, Vol. 24, no 11, p. 1562-1567Article in journal (Refereed)
    Abstract [en]

    We investigated whether self-ratings of health are affected by a symptom rating. A diary including a one-item self-rating of health ("pre-self-rated health"; 1 = excellent, 7 = very poor), a subsequent 26-item rating of symptoms, and thereafter a second (identical) health rating ("post-self-rated health") was completed by 820 persons 21 times. Self-rated health worsened significantly ( p < .0001) after the symptom rating, from 2.72 pre-self-rated health (95% confidence interval: 2.70-2.74) to 2.77 post-self-rated health (95% confidence interval: 2.75-2.79) and more so in persons who reported more symptoms ( b = .058, p < .05). The results support the notion that subjective health perception is influenced by attending to symptoms, especially so in persons with a high symptom burden.

  • 7. Anund, Anna
    et al.
    Ahlström, Christer
    Fors, Carina
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Are professional drivers less sleepy than non-professional drivers?2018In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 44, no 1, p. 88-95Article in journal (Refereed)
    Abstract [en]

    Objective It is generally believed that professional drivers can manage quite severe fatigue before routine driving performance is affected. In addition, there are results indicating that professional drivers can adapt to prolonged night shifts and may be able to learn to drive without decreased performance under high levels of sleepiness. However, very little research has been conducted to compare professionals and non-professionals when controlling for time driven and time of day.

    Method The aim of this study was to use a driving simulator to investigate whether professional drivers are more resistant to sleep deprivation than non-professional drivers. Differences in the development of sleepiness (self-reported, physiological and behavioral) during driving was investigated in 11 young professional and 15 non-professional drivers.

    Results Professional drivers self-reported significantly lower sleepiness while driving a simulator than nonprofessional drivers. In contradiction, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness. They also drove faster. The reason for the discrepancy in the relation between the different sleepiness indicators for the two groups could be due to more experience to sleepiness among the professional drivers or possibly to the faster speed, which might unconsciously have been used by the professionals to try to counteract sleepiness.

    Conclusion Professional drivers self-reported significantly lower sleepiness while driving a simulator than non-professional drivers. However, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness, and they drove faster.

  • 8. Anund, Anna
    et al.
    Ahlström, Christer
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Rumble strips in centre of the lane and the effect on sleepy drivers2011In: Industrial Health, ISSN 0019-8366, E-ISSN 1880-8026, Vol. 49, no 5, p. 549-558Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to describe the effects of sleep loss on behavioural and subjective indicators of sleepiness on a road containing a milled rumble strip in the centre of the lane. Particular attention was paid to behavioural and subjective indicators of sleepiness when using the centre lane rumble strip, and to possible erratic driving behaviour when hitting a rumble strip. In total 9 regular shift workers drove during the morning hours after a full night shift and after a full night sleep. The order was balanced. The experiment was conducted in a moving base driving simulator on rural roads with a road width of 6.5 and 9 meters. Out of the 1,636 rumble strip hits that occurred during the study, no indications of erratic driving behaviour associated with the jolt caused by making contact with the centre lane rumble strip could be found. Comparing the alert condition with the sleep deprived condition, both the standard deviation of lateral position (SDLP) and the Karolinska Sleepiness Scale (KSS) increased for sleepy drivers. For the two road widths, the drivers drove closer to the centre line on the 6.5-meter road. The KSS and the SDLP increased with time on task. This simulator study indicates that rumble strips in the centre of the lane may be an alternative to centreline and edgeline rumble strips on narrow roads.

  • 9. Anund, Anna
    et al.
    Fors, Carina
    Hallvig, David
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Observer Rated Sleepiness and Real Road Driving: An Explorative Study2013In: PLOS ONE, E-ISSN 1932-6203, Vol. 8, no 5, article id e64782Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to explore if observer rated sleepiness (ORS) is a feasible method for quantification of driver sleepiness in field studies. Two measures of ORS were used: (1) one for behavioural signs based on facial expression, body gestures and body movements labelled B-ORS, and (2) one based on driving performance e.g. if swerving and other indicators of impaired driving occurs, labelled D-ORS. A limited number of observers sitting in the back of an experimental vehicle on a motorway about 2 hours repeatedly 3 times per day (before lunch, after lunch, at night) observed 24 participant's sleepiness level with help of the two observer scales. At the same time the participant reported subjective sleepiness (KSS), EOG was recorded (for calculation of blink duration) and several driving measure were taken and synchronized with the reporting. Based on mixed model Anova and correlation analysis the result showed that observer ratings of sleepiness based on drivers' impaired performance and behavioural signs are sensitive to extend the general pattern of time awake, circadian phase and time of driving. The detailed analysis of the subjective sleepiness and ORS showed weak correspondence on an individual level. Only 16% of the changes in KSS were predicted by the observer. The correlation between the observer ratings based on performance (D-ORS) and behavioural signs (B-ORS) are high (r = .588), and the B-ORS shows a moderately strong association (r = .360) with blink duration. Both ORS measures show an association (r>0.45) with KSS, whereas the association with driving performance is weak. The results show that the ORS-method detects the expected general variations in sleepy driving in field studies, however, sudden changes in driver sleepiness on a detailed level as 5 minutes is usually not detected; this holds true both when taking into account driving behaviour or driver behavioural signs.

  • 10. Anund, Anna
    et al.
    Fors, Carina
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    van Leeuwen, Wessel M A
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Countermeasures for fatigue in transportation: A review of existing methods for drivers on road, rail, sea and in aviation2015Report (Other academic)
  • 11. Arnetz, Bengt
    et al.
    Frenzel, Lena
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lisspers, Jan
    The brief fatigue syndrome scale: Validation and utilization in fatigue recovery studies2008In: Fatigue Science for Human Health, Springer , 2008, p. 55-66Chapter in book (Other academic)
  • 12.
    Axelsson, John
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Rehman, Javaid-ur
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Ekman, Rolf
    Miller, Gregory E.
    Höglund, Caroline Olgart
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska institutet, Sweden.
    Effects of Sustained Sleep Restriction on Mitogen-Stimulated Cytokines, Chemokines and T Helper 1/ T Helper 2 Balance in Humans2013In: PLOS ONE, E-ISSN 1932-6203, Vol. 8, no 12, article id e82291Article in journal (Refereed)
    Abstract [en]

    Background: Recent studies suggest that acute sleep deprivation disrupts cellular immune responses by shifting T helper (Th) cell activity towards a Th2 cytokine profile. Since little is known about more long-term effects, we investigated how five days of sleep restriction would affect pro-inflammatory, chemotactic, Th1- and Th2 cytokine secretion. Methods: Nine healthy males participated in an experimental sleep protocol with two baseline sleep-wake cycles (sleep 23.00 - 07.00 h) followed by 5 days with restricted sleep (03.00 - 07.00 h). On the second baseline day and on the fifth day with restricted sleep, samples were drawn every third hour for determination of cytokines/chemokines (tumor necrosis factor alpha (TNF-alpha), interleukin (IL) -1 beta, IL-2, IL-4 and monocyte chemoattractant protein-1 (MCP-1)) after in vitro stimulation of whole blood samples with the mitogen phytohemagglutinin (PHA). Also leukocyte numbers, mononuclear cells and cortisol were analysed. Results: 5-days of sleep restriction affected PHA-induced immune responses in several ways. There was a general decrease of IL-2 production (p<.05). A shift in Th1/Th2 cytokine balance was also evident, as determined by a decrease in IL2/IL4 ratio. No other main effects of restricted sleep were shown. Two significant interactions showed that restricted sleep resulted in increased TNF-alpha and MCP-1 in the late evening and early night hours (p's<.05). In addition, all variables varied across the 24 h day. Conclusions: 5-days of sleep restriction is characterized by a shift towards Th2 activity (i.e. lower 1L-2/IL-4 ratio) which is similar to the effects of acute sleep deprivation and psychological stress. This may have implications for people suffering from conditions characterized by excessive Th2 activity like in allergic disease, such as asthma, for whom restricted sleep could have negative consequences.

  • 13. Barck-Holst, P.
    et al.
    Nilsonne, Å.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Stress Research Institute.
    Hellgren, C.
    Reduced working hours and work-life balance2022In: Nordic Social Work Research, ISSN 2156-857X, E-ISSN 2156-8588, Vol. 12, no 4, p. 450-463Article in journal (Refereed)
    Abstract [en]

    Little is known about how reduced working hours affects the work-life balance of staff in the Swedish social services, or their recovery off-work in terms of specific everyday choices. Staff at a Swedish social work agency participating in a longitudinal trial of work-time reduction in the public services were interviewed about their experiences of work and private life after their work hours were reduced (n = 12). All the interviewees described feeling more positive anticipatory emotions when going to work, several felt that their relationships with colleagues had improved, and most felt their relationships with clients had improved. Several worried less over work, and most perceived the risk for exhaustion syndrome to be lower. Most experienced more positive anticipatory emotions when returning home from work, most of those with children felt that their relationships with their children improved, and those with partners felt their romantic relationships also improved. Several devoted more time to parents and siblings. Most devoted more time to friendship, and all described having more time for recovery activities. Several worried less over their private life. A process that established and maintained a positive work-life balance is suggested by the interviews as a whole, related to increased control over private life, a larger capacity to meet private demands, improved recovery in terms of both quantity and quality, and having access to more sources of formal and informal social support. 

  • 14. Barck-Holst, Peter
    et al.
    Nilsonne, Asa
    Åkerstedt, Torbjorn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Hellgren, Carina
    Reduced working hours and stress in the Swedish social services: A longitudinal study2017In: International Social Work, ISSN 0020-8728, E-ISSN 1461-7234, Vol. 60, no 4, p. 897-913Article in journal (Refereed)
    Abstract [en]

    Stress has been reported among Swedish social workers for over a decade. Survey data from a longitudinal quasi-experimental trial in the public sector of reduced working hours, with a proportional decrease in workload and retained full pay, were used to examine the effect on stress, symptoms of Exhaustion syndrome, psychosocial work characteristics and work-life balance in social workers. Reduced working hours had a positive effect on restorative sleep, stress, memory difficulties, negative emotion, sleepiness, fatigue and exhaustion both on workdays and weekends; on sleep quality on weekends; and on demands, instrumental manager support and work intrusion on private life.

  • 15. Barck-Holst, Peter
    et al.
    Nilsonne, Åsa
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Hellgren, Carina
    Coping with stressful situations in social work before and after reduced working hours, a mixed-methods study2019In: European Journal of Social Work, ISSN 1369-1457, E-ISSN 1468-2664Article in journal (Refereed)
    Abstract [en]

    Little is known about how reduced working hours relate to social work stressors, coping and work-life balance. An exploratory mixed methods study was therefore performed at a Swedish social service agency participating in a quasi-experimental trial of work-time reduction by 25%, with proportionally reduced workload, and retained full-time pay. Social workers that reduced their working hours reported less emotional exhaustion (n = 28, p < 0.05) on the Maslach Burnout Inventory-Human Services Survey, and less reactivity in stressful situations connected to time urgency and irritation (n = 28, p < 0.05) on the Everyday Life Stress Scale. In interviews, the social workers described that despite using effective, problem-focused coping behaviour at work, both before and after work-time reduction, high caseload remained a central stressor, creating time conflicts that exacerbated stressful situations involving emergencies, practical setbacks, client aggression, report deadlines, and managerial stress. In contrast, the work-time reduction was described as fully resolving time conflicts and stress during free-time in situations that involved finding time for friends, household chores, rest, exercise and childcare. Results suggest that reduced working hours lowered emotional exhaustion and situational reactivity by increasing free-time recovery opportunities and decreasing total daily exposure to work stress, but future trials should also compare reduced work-time with reduced caseload.

  • 16. Belenky, Gregory
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Wasensten, Nancy J.
    Introduction2016In: Principles and Practice of Sleep Medicine / [ed] Meir Kryger, Thomas Roth, William C. Dement, Elsevier, 2016, 6, p. 679-681Chapter in book (Other academic)
  • 17.
    Bellavia, Andrea
    et al.
    Karolinska Inst, Inst Environm Med, Unit Nutr Epidemiol.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Bottai, Matteo
    Wolk, Alicja
    Karolinska Inst, Inst Environm Med, Unit Nutr Epidemiol.
    Orsini, Nicola
    Karolinska Inst, Inst Environm Med, Unit Nutr Epidemiol.
    Sleep Duration and Survival Percentiles Across Categories of Physical Activity2014In: American Journal of Epidemiology, ISSN 0002-9262, E-ISSN 1476-6256, Vol. 179, no 4, p. 484-491Article in journal (Refereed)
    Abstract [en]

    The association between long sleep duration and death is not fully understood. Long sleep is associated with low physical activity, which is a strong predictor of death. Our aim was to investigate the association between sleep duration and death across categories of total physical activity in a large prospective cohort of Swedish men and women. We followed a population-based cohort of 70,973 participants (37,846 men and 33,127 women), aged 45-83 years, from January 1998 to December 2012. Sleep duration and physical activity levels were assessed through a questionnaire. We evaluated the association of interest in terms of mortality rates by estimating hazard ratios with Cox regression and in terms of survival by evaluating 15th survival percentile differences with Laplace regression. During 15 years of follow-up, we recorded 14,575 deaths (8,436 men and 6,139 women). We observed a significant interaction between sleep duration and physical activity in predicting death (P < 0.001). Long sleep duration (>8 hours) was associated with increased mortality risk (hazard ratio = 1.24; 95% confidence interval: 1.11, 1.39) and shorter survival (15th percentile difference = -20 months; 95% confidence interval: -30, -11) among only those with low physical activity. The association between long sleep duration and death might be partly explained by comorbidity with low physical activity.

  • 18. Bokenberger, Kathleen
    et al.
    Sjölander, Arvid
    Dahl Aslan, Anna K.
    Karlsson, Ida K.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Pedersen, Nancy L.
    Shift work and risk of incident dementia: a study of two population-based cohorts2018In: European Journal of Epidemiology, ISSN 0393-2990, E-ISSN 1573-7284, Vol. 33, no 10, p. 977-987Article in journal (Refereed)
    Abstract [en]

    This study aimed to investigate the association between shift work and incident dementia in two population-based cohorts from the Swedish Twin Registry (STR). The STR-1973 sample included 13,283 participants born 1926-1943 who received a mailed questionnaire in 1973 that asked about status (ever/never) and duration (years) of shift work employment. The Screening Across the Lifespan Twin (SALT) sample included 41,199 participants born 1900-1958 who participated in a telephone interview in 1998-2002 that asked about night work status and duration. Dementia diagnoses came from Swedish patient registers. Cox proportional-hazards regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI). Potential confounders such as age, sex, education, diabetes, cardiovascular disease and stroke were included in adjusted models. In genotyped subsamples (n = 2977 in STR-1973; n = 10,366 in SALT), APOE epsilon 4 status was considered in models. A total of 983 (7.4%) and 1979 (4.8%) dementia cases were identified after a median of 41.2 and 14.1 years follow-up in the STR-1973 and SALT sample, respectively. Ever shift work (HR 1.36, 95% CI 1.15-1.60) and night work (HR 1.12, 95% CI 1.01-1.23) were associated with higher dementia incidence. Modest dose-response associations were observed, where longer duration shift work and night work predicted increased dementia risk. Among APOE epsilon 4 carriers, individuals exposed to 20 years of shift work and night work had increased dementia risk compared to day workers. Findings indicate that shift work, including night shift work, compared to non-shift jobs is associated with increased dementia incidence. Confirmation of findings is needed.

  • 19. Bokenberger, Kathleen
    et al.
    Ström, Peter
    Aslan, Anna K. Dahl
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Pedersen, Nancy L.
    Shift work and cognitive aging: a longitudinal study2017In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 43, no 5, p. 485-493Article in journal (Refereed)
    Abstract [en]

    Objectives The few studies of shift work and late life cognitive functioning have yielded mixed findings. The aim of the present study is to estimate the association between shift-work experience and change in cognitive performance before and after retirement age among older adults who were gainfully employed. Methods Five hundred and ninety five participants with no dementia were followed up for a mean of 17.6 standard deviation (SD) 8.8 years from a Swedish population-based sample. Participants had self-reported information on any type of shift-work experience (ever/never) in 1984 and measures of cognitive performance (verbal, spatial, memory, processing speed, and general cognitive ability) from up to 9 waves of cognitive assessments during 1986-2012. Night work history (ever/never) from 1998-2002 was available from a subsample (N = 320). Early adult cognitive test scores were available for 77 men. Results In latent growth curve modeling, there were no main effects of any-type or night shift work on the mean scores or rate of change in any of the cognitive domains. An interaction effect between any-type shift work and education on cognitive performance at retirement was noted. Lower-educated shift workers performed better on cognitive tests than lower-educated day workers at retirement. Sensitivity analyses, however, indicated that the interactions appeared to be driven by selection effects. Lower-educated day workers demonstrated poorer cognitive ability in early adulthood than lower-educated shift workers, who may have selected jobs entailing higher cognitive demand. Conclusion There was no difference in late-life cognitive aging between individuals with a history of working shifts compared to those who had typical day work schedules during midlife.

  • 20. Bokenberger, Kathleen
    et al.
    Ström, Peter
    Dahl Aslan, Anna K.
    Johansson, Anna L. V.
    Gatz, Margaret
    Pedersen, Nancy L.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Association Between Sleep Characteristics and Incident Dementia Accounting for Baseline Cognitive Status: A Prospective Population-Based Study2017In: The journals of gerontology. Series A, Biological sciences and medical sciences, ISSN 1079-5006, E-ISSN 1758-535X, Vol. 72, no 1, p. 134-139Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Although research has shown that sleep disorders are prevalent among people with dementia, the temporal relationship is unclear. We investigated whether atypical sleep characteristics were associated with incident dementia while accounting for baseline cognitive functioning.

    METHODS: Screening Across the Lifespan Twin (SALT) study participants were 11,247 individuals from the Swedish Twin Registry who were at least 65 years at baseline (1998-2002). Sleep and baseline cognitive functioning were assessed via the SALT telephone screening interview. Data on dementia diagnoses came from national health registers. Cox regression was performed to estimate hazard ratios for dementia.

    RESULTS: After 17 years of follow-up, 1,850 dementia cases were identified. Short (≤6 hours) and extended (>9 hours) time in bed (TIB) compared to the middle reference group (hazard ratio = 1.40, 95% confidence interval = 1.06-1.85; hazard ratio = 1.11, 95% confidence interval = 1.00-1.24, respectively) and rising at 8:00 AM or later compared to earlier rising (hazard ratio = 1.12, 95% confidence interval = 1.01-1.24) were associated with higher dementia incidence. Bedtime, sleep quality, restorative sleep, and heavy snoring were not significant predictors. Findings stratified by baseline cognitive status indicated that the association between short TIB and dementia remained in those cognitively intact at the start.

    CONCLUSIONS: Short and extended TIB and delayed rising among older adults predicted increased dementia incidence in the following 17 years. The pattern of findings suggests that extended TIB and late rising represent prodromal features whereas short TIB appeared to be a risk factor for dementia.

  • 21. Bonde, Jens Peter
    et al.
    Hansen, Johnni
    Kolstad, Henrik A.
    Mikkelsen, Sigurd
    Olsen, Jorgen H.
    Blask, David E.
    Harma, Mikko
    Kjuus, Helge
    de Koning, Harry J.
    Olsen, Jorn
    Moller, Morten
    Schernhammer, Eva S.
    Stevens, Richard G.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Work at night and breast cancer - report on evidence-based options for preventive actions2012In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 38, no 4, p. 380-390Article in journal (Refereed)
    Abstract [en]

    In 2007, the International Agency for Research on Cancer classified shift work involving circadian disruption as probably carcinogenic to humans (group 2A), primarily based on experimental and epidemiologic evidence for breast cancer. In order to examine options for evidence-based preventive actions, 16 researchers in basic, epidemiological and applied sciences convened at a workshop in Copenhagen 26-27 October 2011. This paper summarizes the evidence from epidemiological and experimental studies and presents possible recommendations for prevention of the effects of night work on breast cancer. Among those studies that quantified duration of shift work, there were statistically significant elevations in risk only after about 20 years working night shift. It is unclear from these studies whether or not there is a modest but real elevated risk for shorter durations. Hence, restriction of the total number of years working night shift could be one future preventive recommendation for shift workers. The diurnal secretion of melatonin by the pineal gland with peak in secretory activity during the night is a good biochemical marker of the circadian rhythm. Disruption of the diurnal melatonin secretion pattern can be diminished by restricting the number of consecutive night shifts. Reddish light and reduced light intensity during work at night could potentially help diminish the inhibitory activity of light with strong intensity on the melatonin secretion, but further mechanistic insight is needed before definite recommendations can be made. Earlier or more intensive mammography screening among female night shift worker is not recommended because the harm benefit ratio in this age group may not be beneficial. Preventive effects of melatonin supplementation on breast cancer risk have not been clearly documented, but may be a promising avenue if a lack of side effects can be shown even after long-term ingestion. Women with previous or current breast cancer should be advised not to work night shifts because of strong experimental evidence demonstrating accelerated tumor growth by suppression of melatonin secretion. Work during the night is widespread worldwide. To provide additional evidence-based recommendations on prevention of diseases related to night shift work, large studies on the impact of various shift schedules and type of light on circadian rhythms need to be conducted in real work environments.

  • 22. Dahlgren, A.
    et al.
    van Leeuwen, Wessel M. A.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kircher, A.
    Lüthöft, M.
    Barnett, M.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fatiqueat sea: a simulator study of sleepiness, sleep and neurobehavioural performance during different watch schedules2013Conference paper (Refereed)
  • 23.
    Dahlgren, Anna
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology. National Institute for Psychosocial Medicine, Stockholm.
    Kecklund, Göran
    National Institute for Psychosocial Medicine, Stockholm.
    Åkerstedt, Torbjörn
    National Institute for Psychosocial Medicine, Stockholm.
    Overtime work and its effects on sleep, sleepiness, cortisol and blood pressure in an experimental field study2006In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 32, no 4, p. 318-327Article in journal (Refereed)
    Abstract [en]

    Objectives Previous studies of long workhours and their effects on stress, sleep, and health show inconclusive results. This inconclusiveness may be partly due to methodological problems such as the use of between-group designs or comparisons before and after reorganizations. In addition, stress is usually a confounder. A within-person design was used to examine the effects of working 8- or 12-hour shifts in the absence of additional stress. Methods In an experimental field study, 16 white-collar workers [9 women, mean age 45.9 (SD 15) years] undertook one workweek with normal workhours (8 hours) and 1 week of overtime with 4 extra hours of regular worktasks (12 hours). The participants wore actigraphs, rated sleepiness (Karolinska Sleepiness Scale) and stress throughout the day, and rated workload and how exhausted they felt. Saliva samples were collected on Mondays and Thursdays for cortisol analysis. On these days, ambulatory heart rate and blood pressure were also measured for 24 hours. Results Overtime was associated with higher levels of exhaustion. Sleepiness showed a significant interaction between conditions, with higher levels at the end of the workweek featuring overtime. Total sleep time was shorter in the overtime week. There were no significant differences between ratings of stress and workload. Cortisol showed a circadian variation but no main effect of condition. Conclusions One week of overtime work with a moderate workload produced no main effects on physiological stress markers. Nevertheless, sleep was negatively affected, with shorter sleeps during overtime work and greater problems with fatigue and sleepiness.

  • 24.
    Dahlgren, Anna
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology. National Institute for Psychosocial Medicine.
    Åkerstedt, Torbjörn
    National Institute for Psychosocial Medicine.
    Kecklund, Göran
    National Institute for Psychosocial Medicine.
    Individual differences in the diurnal cortisol response to stress2004In: Chronobiology International, ISSN 0742-0528, E-ISSN 1525-6073, Vol. 21, no 6, p. 913-922Article in journal (Refereed)
    Abstract [en]

    The objectives of this study were to explore individual differences associated with diverse reactions in cortisol secretion under different stress levels. This study was part of a larger project concerning working hours and health. Thirty-four whitecollar workers participated under two different conditions; one work week with a high stress level (H) and one with a lower stress level (L) as measured through self-rated stress during workdays. Based on the morning cortisol concentration during a workday subjects were divided into two groups. One group consisted of subjects whose morning level of cortisol increased in response to the high-stress week, compared to their morning levels in the low-stress condition (Group 1). The other group consisted of subjects whose morning cortisol response was the opposite, with a lower level under the high stress condition (Group 2). Subjects wore actiwatches, completed a sleep diary, and rated their sleepiness and stress for one work week in each condition, i.e., high and low stress. Saliva samples for measures of cortisol were collected on a Wednesday. Group 2 reported higher workload, fatigue, and exhaustion during both weeks. Since there were no differences in perceived stress, neither within nor between groups, the data indicate that there are other factors influencing morning cortisol. The results suggest that one component modulating the cortisol response might be the level of exhaustion, probably related to work overload. Higher levels of stress in exhausted individuals might suppress morning cortisol levels.

  • 25. Danielsson, Maria
    et al.
    Heimerson, Inger
    Lundberg, Ulf
    Stockholm University, Faculty of Social Sciences, Centre for Health Equity Studies (CHESS). Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Perski, Aleksander
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Stefansson, Claes-Göran
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Psychosocial stress and health problems: Health in Sweden: The National Public Health Report 2012. Chapter 62012In: Scandinavian Journal of Public Health, ISSN 1403-4948, E-ISSN 1651-1905, Vol. 40, no 9, p. 121-134Article in journal (Refereed)
    Abstract [en]

    Stress can be defined as an imbalance between demands placed on us and our ability to manage them. The body’s stress system is adapted to confront sudden physical threats. Today, however, we are increasingly exposed to prolonged mental and psychosocial stress. Prolonged stress can give rise to a range of problems: poor performance, chronic fatigue, disinterest, dejection, memory disturbances, sleep problems, numbness and diffuse muscle pains. These symptoms may eventually be followed by depression, post-traumatic stress disorder and chronic fatigue syndrome, and ultimately chronic pain conditions, cardiovascular disease and diabetes. Sleep is a vital counterbalance to stress as it enables the body to recover properly. Good sleep is thus essential to our ability to cope with stress and stay healthy.

    The decline in the mental wellbeing of the population since the 1980s has been accompanied by a rise in the number of pain complaints. A similar development in respect of symptoms such as anxiousness, nervousness and anxiety, constant fatigue and neck and shoulder pain and sleeping problems has been observed in the population. This increase, which continued throughout the 1990s and culminated in 2001, was followed by a slight fall. However, there was no decline among young people in the early 2000s. Rather, the number of complaints continued to increase.

    Since the mid-1990s, the proportion of people suffering from stress symptoms has risen and fallen in step with employment levels. Since the beginning of the 1980s, growing numbers of people in gainful employment have experienced their work as hectic and mentally taxing. This may indicate that the balance between healthy and unhealthy factors impacting the actively employed has tilted towards less favourable conditions. Mental stress at work has increased among women and men, particularly among county council employees. Repeated organisational restructuring may explain why hectic and mentally taxing work has become more commonplace. Mental ill-health along with musculoskeletal disorders are the most frequent diagnoses in connection with newly granted disability pensions. Sickness absence trends largely reflect the trend in stress symptoms.

  • 26. Dawson, Drew
    et al.
    Ian Noy, Y.
    Härmä, Mikko
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Belenky, Gregory
    Modelling fatigue and the use of fatigue models in work settings2011In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 43, no 2, p. 549-564Article in journal (Refereed)
    Abstract [en]

    In recent years, theoretical models of the sleep and circadian system developed in laboratory settings have been adapted to predict fatigue and, by inference, performance. This is typically done using the timing of prior sleep and waking or working hours as the primary input and the time course of the predicted variables as the primary output. The aim of these models is to provide employers, unions and regulators with quantitative information on the likely average level of fatigue, or risk, associated with a given pattern of work and sleep with the goal of better managing the risk of fatigue-related errors and accidents/incidents. The first part of this review summarises the variables known to influence workplace fatigue and draws attention to the considerable variability attributable to individual and task variables not included in current models. The second part reviews the current fatigue models described in the scientific and technical literature and classifies them according to whether they predict fatigue directly by using the timing of prior sleep and wake (one-step models) or indirectly by using work schedules to infer an average sleep-wake pattern that is then used to predict fatigue (two-step models). The third part of the review looks at the current use of fatigue models in field settings by organizations and regulators. Given their limitations it is suggested that the current generation of models may be appropriate for use as one element in a fatigue risk management system. The final section of the review looks at the future of these models and recommends a standardised approach for their use as an element of the 'defenses-in-depth' approach to fatigue risk management.

  • 27. Di Milia, Lee
    et al.
    Rogers, Naomi L.
    Åkerstedt, Torbjorn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sleepiness, long distance commuting and night work as predictors of driving performance2012In: PLOS ONE, E-ISSN 1932-6203, Vol. 7, no 9, p. e45856-Article in journal (Refereed)
    Abstract [en]

    Few studies have examined the effect of working night shift and long distance commuting. We examined the association between several sleep related and demographic variables, commuting distance, night work and use of mobile phones on driving performance. We used a prospective design to recruit participants and conducted a telephone survey (n = 649). The survey collected demographic and journey details, work and sleep history and driving performance concerning the day the participant was recruited. Participants also completed the Karolinska Sleepiness Scale and the Epworth Sleepiness Scale. Night workers reported significantly more sleepiness, shorter sleep duration and commuting longer distances. Seven variables were significant predictors of lane crossing. The strongest predictor was acute sleepiness (OR = 5.25, CI, 1.42-19.49, p < 0.01) followed by driving >= 150 kms (OR = 3.61, CI, 1.66-7.81, p < 0.001), obtaining less than 10 hours sleep in the previous 48 hours (OR = 2.58, CI, 1.03-6.46, p < 0.05), driving after night shift (OR = 2.19, CI, 1.24-3.88, p < 0.001), being <43 years old (OR = 1.95, CI, 1.11-3.41, p < 0.05) and using mobile phones during the journey (OR = 1.90, CI, 1.10-3.27, p < 0.05). Sleep related variables, long-distance commuting and night work have a major impact on lane crossing. Several interventions should be considered to reduce the level of sleepiness in night workers.

  • 28.
    D'Onofrio, Paolo
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Stress Research Institute. Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Jernelov, Susanna
    Rosen, Ann
    Blom, Kerstin
    Kaldo, Viktor
    Schwarz, Johanna F. A.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Stress Research Institute. Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Stress Research Institute. Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    The Polysomnographical Meaning of Changed Sleep Quality-A Study of Treatment with Reduced Time in Bed2023In: Brain Sciences, ISSN 2076-3425, E-ISSN 2076-3425, Vol. 13, no 10, article id 1426Article in journal (Refereed)
    Abstract [en]

    Background: Reports of poor sleep are widespread, but their link with objective sleep (polysomnography-PSG) is weak in cross-sectional studies. In contrast, the purpose of this study was to investigate the association between changes in subjective and objective sleep variables using data from a study of the reduction in time in bed (TIB). Methods: One sleep recording was carried out at baseline and one at treatment week 5 (end of treatment) (N = 34). Results: The Karolinska Sleep Quality Index improved and was correlated with improvement in sleep efficiency (r = 0.41, p < 0.05) and reduction in TIB (r = -0.47, p < 0.01) and sleep latency (r = 0.36, p < 0.05). The restorative sleep index showed similar results. Improvements in the insomnia severity index (ISI) essentially lacked correlations with changes in the PSG variables. It was suggested that the latter may be due to the ISI representing a week of subjective sleep experience, of which a single PSG night may not be representative. Conclusions: It was concluded that changes in the subjective ratings of sleep are relatively well associated with changes in the PSG-based sleep continuity variables when both describe the same sleep.

  • 29. Eckerberg, Berndt
    et al.
    Lowden, Arne
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Nagai, Roberta
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Melatonin treatment effects on adolescent students' sleep timing and sleepiness in a placebo-controlled crossover study2012In: Chronobiology International, ISSN 0742-0528, E-ISSN 1525-6073, Vol. 29, no 9, p. 1239-1248Article in journal (Refereed)
    Abstract [en]

    During the last few decades, the incidence of sleep-onset insomnia, due to delay of circadian phase, has increased substantially among adolescents all over the world. We wanted to investigate whether a small dose of melatonin given daily, administered in the afternoon, could advance the sleep timing in teenagers. Twenty-one students, aged 14-19 yrs, with sleep-onset difficulties during school weeks were recruited. The study was a randomized, double blind, placebo (PL)-controlled crossover trial, lasting 5 wks. During the first 6 d in wks 2 and 4, the students received either PL or melatonin (1 mg) capsules between 16:30 and 18:00 h. During the first 6 d of wk 5, all students received melatonin. Wks 1 and 3 were capsule-free. In the last evening of each week and the following morning, the students produced saliva samples at home for later melatonin analysis. The samples were produced the same time each week, as late as possible in the evening and as early as possible in the morning. Both the student and one parent received automatic mobile text messages 15 min before saliva sampling times and capsule intake at agreed times. Diaries with registration of presumed sleep, subjective sleepiness during the day (Karolinska Sleepiness Scale, KSS) and times for capsule intake and saliva samplings were completed each day. Primary analysis over 5 wks gave significant results for melatonin, sleep and KSS. Post hoc analysis showed that reported sleep-onset times were advanced after melatonin school weeks compared with PL school weeks (p  <  .005) and that sleep length was longer (p  <  .05). After the last melatonin school week, the students fell asleep 68 min earlier and slept 62 min longer each night compared with the baseline week. Morning melatonin values in saliva diminished compared with PL (p  <  .001) and evening values increased (p  <  .001), indicating a possible sleep phase advance. Compared with PL school weeks, the students reported less wake up (p  <  .05), less school daytime sleepiness (p  <  .05) and increased evening sleepiness (p  <  .005) during melatonin weeks. We conclude that a small dose of melatonin given daily, administered in the afternoon, could advance the sleep timing and make the students more alert during school days even if they continued their often irregular sleep habits during weekends.

  • 30. Filtness, Ashleigh J.
    et al.
    Anund, Anna
    Fors, Carina
    Ahlström, Christer
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud University Nijmegen, Netherlands.
    Sleep-related eye symptoms and their potential for identifying driver sleepiness2014In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 23, no 5, p. 568-575Article in journal (Refereed)
    Abstract [en]

    The majority of individuals appear to have insight into their own sleepiness, but there is some evidence that this does not hold true for all, for example treated patients with obstructive sleep apnoea. Identification of sleep-related symptoms may help drivers determine their sleepiness, eye symptoms in particular show promise. Sixteen participants completed four motorway drives on two separate occasions. Drives were completed during daytime and night-time in both a driving simulator and on the real road. Ten eye symptoms were rated at the end of each drive, and compared with driving performance and subjective and objective sleep metrics recorded during driving. 'Eye strain', 'difficulty focusing', 'heavy eyelids' and 'difficulty keeping the eyes open' were identified as the four key sleep-related eye symptoms. Drives resulting in these eye symptoms were more likely to have high subjective sleepiness and more line crossings than drives where similar eye discomfort was not reported. Furthermore, drivers having unintentional line crossings were likely to have 'heavy eyelids' and 'difficulty keeping the eyes open'. Results suggest that drivers struggling to identify sleepiness could be assisted with the advice 'stop driving if you feel sleepy and/or have heavy eyelids or difficulty keeping your eyes open'.

  • 31. Flo, Elisabeth
    et al.
    Pallesen, Stale
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Mageroy, Nils
    Moen, Bente Elisabeth
    Gronli, Janne
    Nordhus, Inger Hilde
    Bjorvatn, Bjorn
    Shift-related sleep problems vary according to work schedule2013In: Occupational and Environmental Medicine, ISSN 1351-0711, E-ISSN 1470-7926, Vol. 70, no 4, p. 238-245Article in journal (Refereed)
    Abstract [en]

    Objectives Shift-related sleep and sleepiness problems may be due to characteristics of both shifts (ie, day, evening and night shifts) and work schedules (ie, permanent vs rotational schedules). The Bergen Shift Work Sleep Questionnaire (BSWSQ) was used to investigate associations between shift-related sleep problems and work schedules. Methods 1586 nurses completed the BSWSQ. Participants who, in relation to a shift, 'often' or 'always' experienced both a sleep problem and a tiredness/sleepiness problem were defined as having shift-related insomnia (separate for day, evening and night shifts and rest-days). Logistic regression analyses were conducted for day, evening, night, and rest-day insomnia with participants on both permanent and rotational schedules. Results Shift-related insomnia differed between the work schedules. The evening shift insomnia was more prevalent in the two-shift rotation schedule than the three-shift rotation schedule (29.8% and 19.8%, respectively). Night shift insomnia showed higher frequencies among three-shift rotation workers compared with permanent night workers (67.7% and 41.7%, respectively). Rest-day insomnia was more prevalent among permanent night workers compared with two- and three-shift rotations (11.4% compared with 4.2% and 3.6%, respectively). Conclusions The prevalences of shift-related insomnia differed between the work schedules with higher frequencies for three-shift rotations and night shifts. However, sleep problems were present in all shifts and schedules. This suggests that both shifts and work schedules should be considered in the study of shift work-related sleep problems.

  • 32. Garde, Anne Helene
    et al.
    Karlson, Berndt
    Hansen, Åse Marie
    Persson, Roger
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sleep and salivary cortisol2012In: The role of saliva cortisol measurement in health and disease / [ed] Margareta Kristenson, Peter Garvin, Ulf Lundberg, Bentham eBooks, 2012, p. 116-128Chapter in book (Other academic)
    Abstract [en]

    The aim of the present chapter was to analyze whether measures of cortisol in saliva were associated with measures of sleep and to explore if divergent results were related to underlying differences in theoretic assumptions and methods. Measures of sleep quality included sleep duration, overall sleep quality, difficulty falling asleep, disturbed sleep, and sleep deprivation. Twenty-three papers were found to fulfil the inclusion criteria. Cortisol measures were grouped into single time points at different times during the day, deviations at different time periods during the day, reactivity and recovery after a standardized laboratory test, area under the curve and response to dexamethasone test. A large proportion of the studies included showed nonsignificant findings, which, in several cases, may be a result of low power. The most consistent results were a positive association between sleep duration and single measures of salivary cortisol at awakening, which was observed in 3 studies. In these studies, sleep duration was also associated with low evening cortisol levels, steep diurnal deviation of cortisol and/or high area under the curve. Together these findings suggest that longer sleep duration is related to a more dynamic cortisol secretion. Two of the 6 studies on disturbed or restless sleep showed relations to flat diurnal deviation and low laboratory stress test reactivity. This to some extent corroborates the findings on sleep duration. However, the many nonsignificant findings as well as the theoretical and methodological differences (e.g., heterogeneity in measures) complicate comparisons. Conflicting results may be at least partially due to differences in methods and underlying assumptions.

  • 33.
    Garefelt, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lowden, Arne
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Insomnia among day and shift workers above the arctic circle – associations with stress, light deprivation and underground work2013Conference paper (Other academic)
  • 34.
    Garefelt, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Platts, Loretta G.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Hyde, Martin
    Magnusson Hanson, Linda L.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Westerlund, Hugo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Reciprocal relations between work stress and insomnia symptoms: A prospective study2020In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 29, no 2, article id e12949Article in journal (Refereed)
    Abstract [en]

    Work stress and poor sleep are closely related in cross-sectional data, but evidence from prospective data is limited. We analysed how perceived stress and work stressors (work demands, decision authority and workplace social support) are related to key dimensions of insomnia over time, using structural equation modelling. Biennial measurements from a large sample of the working population in Sweden enabled us to analyse both the relationship from stress to sleep as well as that from sleep to stress. Overall, we found reciprocal relations between insomnia and all four stress measures. However, looking at the relation between each dimension of insomnia and each stress measure, there were some differences in direction of effects. In the direction from stress to sleep, all work stressors as well as perceived stress predicted both difficulties initiating sleep and difficulties maintaining sleep. The same was found for non-restorative sleep, with the exception for decision authority. In the opposite direction, difficulties maintaining sleep predicted increased levels of work demands and perceived stress. Difficulties initiating sleep stood out among the insomnia symptoms as not predicting any of the stress measures, while non-restorative sleep was the only symptom predicting all stress measures. The results advance the understanding of the stress-sleep relationship and indicate a potential vicious circle between insomnia and perceived stress as well as work stressors, suggesting that the workplace could be an arena for interventions to alleviate insomnia.

  • 35.
    Garefelt, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Westerlund, Hugo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Magnusson Hanson, Linda L.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sverke, Magnus
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Work and sleep – a prospective study of psychosocial work factors, physical work factors and work scheduling2014In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 23, no S1, p. 218-218, article id P706Article in journal (Refereed)
  • 36.
    Garefelt, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Westerlund, Hugo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Magnusson Hanson, Linda
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sverke, Magnus
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Work and sleep – the effects of stress, physical work environment and work hours: A prospective study using the SLOSH database2013Conference paper (Other academic)
    Abstract [en]

    METHODS: Data was derived from two waves of SLOSH (The Swedish Longitudinal Occupational Survey of Health), a representative sample of the working population in Sweden. Respondents in the present study sample were gainfully employed in both 2008 (T1) and in 2010 (T2), and without sleep disturbances at T1 (n=5741, 54 % women, 46 % men, aged 24-72 years). Between T1 and T2 a total number of 441 people (8 %) developed sleep disturbances. Logistic regression was made in five hierarchical models with new cases of disturbed sleep as the dependent variable. Factors studied were changes in physical work environment, work hours, demands, control, support and stress between T1 and T2; increased or decreased levels of exposure, as well as consistently high or low levels. RESULTS: In the fully adjusted model, stress showed the strongest association with new cases of disturbed sleep. Increased stress levels had an OR of 2.9 (95% CI 2.0-4.3) and consistently high levels of stress had an OR of 2.8 (1.9-4.2). Increased levels of demands showed a weaker association, OR=1.8 (1.2-2.6), whereas consistently high levels of demands did not show significant results. Decreased levels of social support showed an increased OR of 2.3 (1.6-3.3), as did consistently low levels of social support with an OR of 1.6 (1.1-2.3). Neither changes in control nor changes in work hours showed any significant results. Increased exposure to excessive heat, cold or draught showed a OR of 1.7 (1.1-2.8) whereas changes in heavy physical labour, noise at work, and poor or excessively bright light did not show an association with new cases of sleep disturbances in the fully adjusted model.

  • 37.
    Gerhardsson, Andreas
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Work and organizational psychology.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Emotional working memory in older adults after total sleep deprivation2017In: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 40, no Suppl. 1, p. e110-e110Article in journal (Refereed)
    Abstract [en]

    Introduction: Even though the occurrence of sleep problems increases with age, few studies have focused on the cognitive effects of acute sleep deprivation in elderly. Most previous research indicate that, compared to young, older adults show less impairment in e.g. attention after sleep deprivation. However, little is known of whether the same pattern holds for higher cognitive functions. In addition, while old age is usually related to a general decrease in working memory abilities, performance on working memory tasks may differ depending on the emotional valence of the stimuli, where positive stimuli seem to be beneficial for working memory performance in older adults. The aim of the present study was to investigate the effect of sleep deprivation on emotional working memory in older adults using two levels of working memory load.

    Materials and methods: A healthy sample of 48 old adults (MAge=66.69 years, SDAge=3.44 years) was randomized into a total sleep deprivation group (TSD; n=24) or a sleep control group (SC; n=24). They performed a working memory task (n-back) containing positive, negative and neutral pictures in a low (1-back) and a high (3-back) working memory load condition. Performance was measured as Accuracy (d'), Omissions and Reaction Time (RT).

    Results: For the d' and Omissions we performed two separate 2x2x3 (sleep, working memory load, valence) repeated measures analyses of variance (rmANOVA). For the RTs, we applied a mixed-effects model. For both d' and RT we found no effect of sleep deprivation (Ps > .05). For valence, we found main effects on both d' (F1,46 = 5.56, P=.005) and RT (F1,95.7 = 4.84, P=.01). d' did not differ for positive and neutral pictures, but was in both cases significantly better than for negative pictures. RTs were significantly faster for positive pictures. However, a working memory loadvalence interaction (F1,95.7 = 4.50, P=.01) further revealed an effect of valence in the low, but not in the high load condition. In the low load condition, RTs were faster for positive than for neutral pictures and faster for neutral than for negative pictures. There was no significant effect of Omissions.

    Conclusions: Our results showed that emotional working memory performance was not significantly affected by one night of sleep deprivation in older adults, which contrast what we found in a sample of young adults from the same project. In line with previous research, our results indicate a beneficial effect of positive stimuli on working memory in older adults. This effect was present in both groups and most pronounced for reaction times in the condition with a lower cognitive demand. We can conclude that, among older adults, the working memory performance is not impaired by sleep deprivation and that the benefits of positive stimuli on working memory seem intact. These findings contribute to a better understanding of older adults' cognitive functioning after sleep deprivation.

  • 38.
    Gerhardsson, Andreas
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology. Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Positivity Effect and Working Memory Performance Remains Intact in Older Adults After Sleep Deprivation2019In: Frontiers in Psychology, E-ISSN 1664-1078, Vol. 10, article id 605Article in journal (Refereed)
    Abstract [en]

    Background: Older adults perform better in tasks which include positive stimuli, referred to as the positivity effect. However, recent research suggests that the positivity effect could be attenuated when additional challenges such as stress or cognitive demands are introduced. Moreover, it is well established that older adults are relatively resilient to many of the adverse effects of sleep deprivation. Our aim was to investigate if the positivity effect in older adults is affected by one night of total sleep deprivation using an emotional working memory task.

    Methods: A healthy sample of 48 older adults (60-72 years) was either sleep deprived for one night (n = 24) or had a normal night's sleep (n = 24). They performed an emotional working memory n-back (n = 1 and 3) task containing positive, negative and neutral pictures.

    Results: Performance in terms of accuracy and reaction times was best for positive stimuli and worst for negative stimuli. This positivity effect was not altered by sleep deprivation. Results also showed that, despite significantly increased sleepiness, there was no effect of sleep deprivation on working memory performance. A working memory load x valence interaction on the reaction times revealed that the beneficial effect of positive stimuli was only present in the 1-back condition.

    Conclusion: While the positivity effect and general working memory abilities in older adults are intact after one night of sleep deprivation, increased cognitive demand attenuates the positivity effect on working memory speed.

  • 39.
    Gerhardsson, Andreas
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Positivity effect in older adults after sleep deprivation2019Conference paper (Other academic)
  • 40.
    Gerhardsson, Andreas
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    The effect of sleep loss on emotional working memory2016In: Abstracts, 2016, Vol. 25(S1), p. 17-18Conference paper (Other academic)
    Abstract [en]

    Objectives: Emotional stimuli differently affect working memory (WM) performance. As sleep deprivation has a known impact on both emotion and WM our aim was to investigate how one night without sleep affects emotional WM performance. Methods: Healthy subjects (n = 56; age 18–30 years) were randomized to a total sleep deprivation (TSD) or a rested control (RC) condition. Subjects rated their affective state and performed a 1 and a 3-back WM task consisting of neutral, positive and negative pictures at 3 pm or 6 pm (balanced) the day after sleep manipulation. Accuracy (d’) and target response time (RT) were used as outcomes. Results: In the TSD condition, subjects rated themselves as less positive (P = 0.006) but not more negative than in the RC condition. In the WM task, TSD had a detrimental effect on accuracy (P = 0.03) regardless of difficulty. Moreover, accuracy was higher in the 1-back than in the 3-back (P < 0.001) and higher for neutral compared to both negative and positive stimuli (Ps < 0.05). RT was faster for positive compared to negative and neutral stimuli (Ps < 0.05). The latter effect was particularly pronounced in the TSD condition as shown by a condition*valence interaction (P < 0.03). Conclusions: One night of total sleep loss impaired emotional WM accuracy. Noticeable, RT was faster for positive stimuli compared to negative and neutral stimuli. This effect was particularly pronounced after sleep loss. This suggests that sleep loss strengthens the opposing effects of positive and negative stimuli on WM performance, possibly due to increased emotion reactivity.

  • 41.
    Gerhardsson, Andreas
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology. Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Effect of sleep deprivation on emotional working memory2019In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 28, no 1, article id e12744Article in journal (Refereed)
    Abstract [en]

    The emotional dysregulation and impaired working memory found after sleep loss can have severe implications for our daily functioning. Considering the intertwined relationship between emotion and cognition in stimuli processing, there could be further implications of sleep deprivation in high‐complex emotional situations. Although studied separately, this interaction between emotion and cognitive processes has been neglected in sleep research. The aim of the present study was to investigate the effect of 1 night of sleep deprivation on emotional working memory. Sixty‐one healthy participants (mean age: 23.4 years) were either sleep deprived for 1 night (n = 30) or had a normal night’s sleep (n = 31). They performed an N‐back task with two levels of working memory load (1‐back and 3‐back) using positive, neutral and negative picture scenes. Sleep deprivation, compared with full night sleep, impaired emotional working memory accuracy, but not reaction times. The sleep‐deprived participants, but not the controls, responded faster to positive than to negative and neutral pictures. The effect of sleep deprivation was similar for both high and low working memory loads. The results showed that although detrimental in terms of accuracy, sleep deprivation did not impair working memory speed. In fact, our findings indicate that positive stimuli may facilitate working memory processing speed after sleep deprivation.

  • 42. Ghilotti, Francesca
    et al.
    Bellocco, Rino
    Trolle Lagerros, Ylva
    Thorson, Anna
    Theorell-Haglöw, Jenny
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Stress Research Institute. Karolinska Institutet, Sweden.
    Lindberg, Eva
    Relationship between sleep characteristics and markers of inflammation in Swedish women from the general population2021In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 30, no 2, article id e13093Article in journal (Refereed)
    Abstract [en]

    Systemic inflammation is thought to mediate the link between sleep and cardiovascular outcomes, but previous studies on sleep habits and inflammation markers have found inconsistent results. This study investigated the relationship between sleep characteristics and C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF alpha). A representative sample of 319 Swedish women was randomly selected from the general population for in-home polysomnography, sleep questionnaire and blood samples. As variables were highly correlated, principal component analysis was used to reduce the number of original variables. Linear regression with log-transformation of the outcomes (lnCRP, lnIL-6 and lnTNF alpha) and quantile regression were fitted to estimate cross-sectional relationships. Multivariable linear regression models suggested a significant association of insomnia symptoms (self-reported) with higher lnCRP levels (beta = 0.11; 95% confidence interval [CI] = 0.02; 0.21), but not with lnIL-6 and lnTNF alpha. From quantile regression analysis we found that a high non-restorative index (subjective) and insomnia symptoms (self-reported) were associated with higher values of CRP, especially in the highest quantiles of the CRP distribution (90th percentile: beta = 0.71; 95% CI = 0.17; 1.24. beta = 1.23; 95% CI = 0.44; 2.02, respectively). Additionally, higher amounts of rapid eye movement (REM) sleep were associated with lower CRP values (90th percentile: beta = -0.80; 95% CI = -0.14; -1.46). In conclusion, sleep disturbances (self-reported), specifically difficulties maintaining sleep and early morning awakenings, but not sleep duration (neither subjective nor objective), were associated with higher CRP levels. No association was found with IL-6 or TNF alpha. Elevated REM sleep was associated with lower CRP levels. The results suggest that inflammation might be an intermediate mechanism linking sleep and health in women.

  • 43. Ghilotti, Francesca
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Stress Research Institute. Karolinska Institutet, Sweden.
    Bellocco, Rino
    Adami, Hans-Olov
    Trolle Lagerros, Ylva
    Prospective study of job stress and risk of infections in Swedish adults2020In: Occupational and Environmental Medicine, ISSN 1351-0711, E-ISSN 1470-7926, Vol. 77, no 10, p. 681-690Article in journal (Refereed)
    Abstract [en]

    Objectives Psychological stress may influence both susceptibility and severity of infections. Although work-related stress is a widespread concern among many employees, few studies have been conducted with the focus on work stressors and infections. We therefore aimed to investigate this association in a prospective cohort study.

    Methods Our study included 25 029 employed individuals who filled-out a questionnaire in September 1997 and were followed through record linkages until retirement or December 2016. Work stress was assessed at baseline using a Swedish version of the Demand-Control Questionnaire, whereas hospital contacts related to infections were identified from the National Patient Register. We fitted extensions of the standard Cox model to account for recurrent infections.

    Results In total, we observed 8257 infections. Individuals in the third tertile of job demand had a 13% higher hazard of infections (HR=1.13; 95% CI=1.03 to 1.24) compared with individuals in the first tertile, specifically an increased incidence of upper respiratory tract infections (HR=1.15; 95% CI=1.00 to 1.33) and urinary tract infections (HR=1.31; 95% CI=1.09 to 1.57) was found. Employees with the highest job control (third tertile) had no lower risk of infections than individuals in the lowest tertile (HR=1.02; 95% CI=0.92 to 1.13). When combining the demand and control dimensions into job strain scale, no association between high job strain and infections was observed (HR=1.08; 95% CI=0.97 to 1.21).

    Conclusion High job demand, but not low job control, is associated with an increased occurrence of infections. No difference was observed in workers with high strain jobs compared with those with low strain jobs.

  • 44. Gonçalves, MA
    et al.
    Amici, R
    Peigneux, P
    Luckas, R
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Cirignotta, FC
    Horne, J
    Léger, D
    McNicholas, W
    Partinen, M
    Téran Santos, J
    Grote, L
    The wake-up bus sleep study: falling asleep at the wheel in 19 European countries2014Conference paper (Other academic)
  • 45. Hallvig, David
    et al.
    Anund, Anna
    Fors, Carina
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Karlsson, Johan G.
    Wahde, Mattias
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Sleepy driving on the real road and in the simulator-A comparison2012In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 50, p. 44-50Article in journal (Refereed)
    Abstract [en]

    Sleepiness has been identified as one of the most important factors contributing to road crashes. However, almost all work on the detailed changes in behavior and physiology leading up to sleep related crashes has been carried out in driving simulators. It is not clear, however, to what extent simulator results can be generalized to real driving. This study compared real driving with driving in a high fidelity, moving base, driving simulator with respect to driving performance, sleep related physiology (using electroencephalography and electrooculography) and subjective sleepiness during night and day driving for 10 participants. The real road was emulated in the simulator. The results show that the simulator was associated with higher levels of subjective and physiological sleepiness than real driving. However, both for real and simulated driving, the response to night driving appears to be rather similar for subjective sleepiness and sleep physiology. Lateral variability was more responsive to night driving in the simulator, while real driving at night involved a movement to the left in the lane and a reduction of speed, both of which effects were absent in the simulator. It was concluded that the relative validity of simulators is acceptable for many variables, but that in absolute terms simulators cause higher sleepiness levels than real driving. Thus, generalizations from simulators to real driving must be made with great caution.

  • 46.
    Hallvig, David
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Anund, Anna
    Fors, Carina
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud University Nijmegen, The Netherlands.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Real driving at night - predicting lane departures from physiological and subjective sleepiness2014In: Biological Psychology, ISSN 0301-0511, E-ISSN 1873-6246, Vol. 101, p. 18-23Article in journal (Refereed)
    Abstract [en]

    Only limited information is available on how driving performance relates to physiological and subjective sleepiness on real roads. This relation was the focus of the present study. 33 volunteers drove for 90min on a rural road during the afternoon and night in an instrumented car, while electroencephalography and electrooculography and lane departures were recorded continuously and subjective ratings of sleepiness were made every 5min (Karolinska Sleepiness Scale - KSS). Data was analyzed using Bayesian multilevel modeling. Unintentional LDs increased during night driving, as did KSS and long blink durations(LBD). Lateral position moved to the left . LDs were predicted by self-reported sleepiness and LBDs across time and were significantly higher in individuals with high sleepiness. Removal of intentional LDs, enhanced the KSS/LD relation. It was concluded that LDs, KSS, and LBDs are strongly increased during night driving and that KSS predicts LDs.

  • 47. Hedenstierna, Louise
    et al.
    Bellocco, Rino
    Ye, Weimin
    Adami, Hans-Olov
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Trolle Lagerros, Ylva
    Hedström, Anna Karin
    Effects of alcohol consumption and smoking on risk for RA: results from a Swedish prospective cohort study2021In: RMD Open, E-ISSN 2056-5933, Vol. 7, no 1, article id e001379Article in journal (Refereed)
    Abstract [en]

    Objective Several, but not all studies, have shown a dose-dependent inverse association with alcohol consumption and rheumatoid arthritis (RA), whereas smoking is an established risk factor for RA. We aimed to study the association between alcohol consumption and RA incidence and investigate a potential interaction between alcohol and smoking habits, regarding RA incidence.

    Methods We used a prospective cohort study, based on 41 068 participants with detailed assessment of alcohol intake, smoking and potential confounders at baseline in 1997. We ascertained a total of 577 incident cases of RA during a mean of 17.7 years of follow-up through linkage to nationwide and essentially complete databases. Multivariate Cox proportional hazards models were used to estimate HR with 95% CI. Interaction on the additive scale between alcohol and smoking was estimated by calculating the attributable proportion due to interaction (AP).

    Results Overall, alcohol consumption was associated with a 30% reduced incidence of RA (HR 0.69, 95% CI 0.55 to 0.86) with a dose-response relationship (p value for trend <0.001) which remained significant after stratification by age and smoking habits. The positive association between smoking and RA incidence was reduced with increasing alcohol consumption (p value for trend <0.001). A synergistic effect was observed between alcohol and smoking (AP 0.40, 95% CI 0.15 to 0.64), indicating that 40% of the cases among the double exposed are due to the interaction per se.

    Conclusions Our findings suggest an inverse association between alcohol consumption and RA incidence, and a synergistic effect between alcohol and smoking.

  • 48. Hedström, A. K.
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Olsson, T.
    Alfredsson, L.
    Shift work influences multiple sclerosis risk2015In: Multiple Sclerosis Journal, ISSN 1352-4585, E-ISSN 1477-0970, Vol. 21, no 9, p. 1195-1199Article in journal (Refereed)
    Abstract [en]

    Background:

    An association between working shift at a young age and subsequent risk for multiple sclerosis (MS) has been observed.

    Objective:

    To investigate whether this finding could be replicated, and to further explore the influence of age at first exposure to shift work.

    Methods:

    Using a Swedish population-based, case-control study (2337 cases and 4904 controls), the incidence of MS among subjects whom had worked shifts was compared with that of those whom had not, by calculating odds ratios (ORs) with 95% confidence intervals (CIs) by means of logistic regression.

    Results:

    The OR of developing MS was 1.5 (95% CI 1.2–1.8) among those whom started working shifts before age 20, whereas a less pronounced association was observed among those whom started working shifts at age 20 or later (OR 1.2; 95% CI 1.1–1.4). The effect of shift work was more pronounced among subjects whom had been exposed at a young age, regardless of the duration between the start of shift work and disease onset.

    Conclusion:

    Some aspects of adolescence seem to be of great importance, regarding the impact of shift work on MS risk. Circadian disruption and sleep deprivation may contribute towards explaining the association; however, the exact mechanisms behind our observations remain to be elucidated.

  • 49. Hedström, Anna Karin
    et al.
    Bellocco, Rino
    Hössjer, Ola
    Stockholm University, Faculty of Science, Department of Mathematics.
    Ye, Weimin
    Trolle Lagerros, Ylva
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Stress Research Institute. Karolinska Institutet, Sweden.
    The relationship between nightmares, depression and suicide2021In: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 77, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Objective: Previous studies investigating the association between nightmares and suicide have yielded different results. We aimed to investigate whether nightmares, directly or indirectly, influence the incidence of suicide.

    Methods: We used a prospective cohort study, based on 40,902 participants with a mean follow-up duration of 19.0 years. Cox proportional hazards models with attained age as time-scale were fitted to estimate hazard ratios (HR) of suicide with 95% confidence intervals (CI) as a function of the presence or absence of depression and nightmares. Mediation analysis was used to asses to what extent the relationship between nightmares and the incidence rate of suicide could be mediated by depression.

    Results: No association was observed between nightmares and the incidence of suicide among participants without depression. Compared with non-depressed participants without nightmares, the incidence of suicide among participants with a diagnosis of depression was similar among those with and without nightmares (HR 12.3, 95% CI 5.55-27.2 versus HR 13.2, 95% CI 7.25-24.1). The mediation analysis revealed no significant effects of nightmares on suicide incidence. However, the incidence of depression during follow-up was higher among those who suffered from nightmares than among those who did not (p < 0.001).

    Conclusions: Our findings indicate that nightmares have no influence on the incidence rate of suicide, but may reflect pre-existing depression. This is supported by a recent discovery of a strong genetic correlation of nightmares with depressive disorders, with no evidence that nightmares would predispose to psychiatric illness or psychological problems. Interventions targeting both depression and nightmares, when these conditions co-occur, may provide additional therapeutic benefit.

  • 50. Hedström, Anna Karin
    et al.
    Bellocco, Rino
    Ye, Weimin
    Lagerros, Ylva Trolle
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Association Between Insomnia And Mortality Is Only Evident Among Long Sleepers2019In: Nature and Science of Sleep, ISSN 1179-1608, Vol. 11, p. 333-342Article in journal (Refereed)
    Abstract [en]

    Background: Previous studies investigating the relationship between insomnia and mortality have been inconsistent. Purpose: We aimed to assess whether nocturnal insomnia symptoms and non-restorative sleep are associated with all-cause mortality and whether they modify the associations between short and long sleep duration and all-cause mortality. Patients and methods: The present report is based on a prospective cohort study of 39,139 participants with a mean follow-up time of 19.6 years. Cox proportional hazard models with attained age as timescale were used to estimate overall mortality hazard ratios (HRs) with 95% confidence intervals (CI) for different categories of sleep duration and insomnia symptoms. Results: Both difficulty initiating sleep and daytime sleepiness were independently associated with increased mortality among those with sleep duration of 9 hrs or more (HR 1.51, 95% CI 1.11-2.07 and HR 1.37, 95% CI 1.03-1.82). Mortality increased with increasing severity of difficulties initiating sleep (p for trend 0.04) and daytime sleepiness (p for trend 0.01) among the long sleepers. None of the insomnia symptoms were associated with mortality among those who reported sleep duration of 8 hrs or less. Conclusion: Long sleep in combination with difficulties initiating sleep and daytime sleepiness, possibly due to psychiatric or physical disorders, was thus associated with increased mortality, whereas long sleep without difficulties falling asleep or daytime sleepiness was not associated with mortality. Our study emphasizes the need to take nocturnal insomnia symptoms and daytime sleepiness into consideration when assessing the influence of sleep duration on mortality. Additional research is needed to elucidate the relationship between long sleep, insomnia and related psychiatric and physical disorders.

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