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  • 101.
    Schwarz, Johanna F. A.
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lindberg, E.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Theorell-Haglöw, J.
    Sleep length misperception and its association to subjective sleep quality and objective sleep duration in a large sample of women2013Conference paper (Refereed)
  • 102.
    Schwarz, Johanna F. A.
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Lindberg, Eva
    Gruber, Georg
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Theorell-Haglöw, Jenny
    Age affects sleep microstructure more than sleep macrostructure2017In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 26, no 3, p. 277-287Article in journal (Refereed)
    Abstract [en]

    It is well known that the quantity and quality of physiological sleep changes across age. However, so far the effect of age on sleep microstructure has been mostly addressed in small samples. The current study examines the effect of age on several measures of sleep macro- and microstructure in 211 women (22–71 years old) of the ‘Sleep and Health in Women’ study for whom ambulatory polysomnography was registered. Older age was associated with significantly lower fast spindle (effect size f2 = 0.32) and K-complex density (f2 = 0.19) during N2 sleep, as well as slow-wave activity (log) in N3 sleep (f2 = 0.21). Moreover, total sleep time (f2 = 0.10), N3 sleep (min) (f2 = 0.10), rapid eye movement sleep (min) (f2 = 0.11) and sigma (log) (f2 = 0.05) and slow-wave activity (log) during non-rapid eye movement sleep (f2 = 0.09) were reduced, and N1 sleep (f2 = 0.03) was increased in older age. No significant effects of age were observed on slow spindle density, rapid eye movement density and beta power (log) during non-rapid eye movement sleep. In conclusion, effect sizes indicate that traditional sleep stage scoring may underestimate age-related changes in sleep.

  • 103.
    Schwarz, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Gerhardsson, Andreas
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Work and organizational psychology.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Age-dependent effects of sleep deprivation on task performance and mind wandering2017In: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 40, no Suppl. 1, article id e297Article in journal (Refereed)
    Abstract [en]

    Introduction: Mind wandering, the drift of attention from the current task at hand to self-generated thought is commonly associated with poorer performance, and could be a potential pathway through which sleep deprivation affects performance. Little is known about this, however. Therefore, the aim of the present study was to address the effect of sleep deprivation on mind wandering and performance in a sustained attention task. In addition, we studied age as moderating factor, since older individuals are generally less prone to mind wandering.

    Materials and methods: Healthy young (18-30years) and older (60-72years) subjects participated in either a normal night sleep (NSD) or a total sleep deprivation (SD) condition, i.e. 4 conditions: NSD (n=31), SD (n=30), NSDold (n = 24), SDold (n= 24). Performance was measured using the Sustained Attention to Response Task, during which 10 thought probes were included that prompted the subjects to answer a question on what they were you just thinking about, using predefined answer alternatives. Mind wandering was quantified as occurrence of task-unrelated thoughts.

    Results: Applying a 2 (age) X 2 (sleep deprivation) ANOVA, significant main effects for sleep deprivation and age were observed for omissions, indicating worse performance after sleep deprivation and in young participants (p's < .05). These main effects were dominated by an age*sleep deprivation interaction (p = .04), which was due to sleep deprivation causing significantly more omission errors in young subjects (Mean ±SEM; NSD: 2.3 ±0.9; SD: 13.1 ±4.1) but not in older subjects (NSDold: 1.9 ±0.4; SDold: 2.8 ±0.9).

    Likewise, main and interaction effects for age and sleep deprivation were significant for task-unrelated thoughts (p's < 0.01). Task unrelated thoughts were significantly more frequent after sleep loss in young (NSD: 1.5 ±0.2; SD: 4.3 ±0.6), but not older subjects (NSDold: 0.3 ±0.2; SDold: 0.5 ±0.2) (interaction age*sleep deprivation p < .01). Young subjects had significantly more task-unrelated thoughts than older, regardless of sleep condition.

    Task-unrelated thoughts correlated with errors of omission (r = 0.65, p < .001). Also, including task unrelated thoughts as covariate in the age * sleep deprivation ANOVA, main and interactions effect of age and sleep deprivation were no longer significant.

    Reaction time was significantly slower in older adults, but no main or interaction effect of sleep deprivation occurred. Errors of commission were not affected by condition.

    Conclusions: The results show that sleep deprivation caused both mind wandering and poorer task performance in young but not older participants. In addition, mind wandering rates correlated with errors of omission, which may indicate that a diminished ability to shut down off-task thoughts after sleep deprivation could be an important pathway to performance decrements after sleep loss. In line with previous research, mind wandering appears to occur less frequently in older individuals compared with younger. This lower occurrence of mind wandering in older subjects may potentially enable them to better maintain performance after sleep deprivation and partially explain the higher resilience of older adults to sleep deprivation.

  • 104.
    Schwarz, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Gerhardsson, Andreas
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Van Leeuwen, Wessel
    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.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    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.
    The effect of sleep loss on the response to acute psychosocial stress in young and elderly2016Conference paper (Refereed)
    Abstract [en]

    Both sleep loss and social stress are risk factors for health and performance ability. It is assumed that sleep and stress are bidirectional linked, but most of the previous research has focused on studying sleep problems as consequence of stress. We believe that it is important to improve our understanding of the reverse connection, which is less studied. This presentation will cover recent experimental human studies that have investigated how sleep loss affects stress responses and whether it makes individuals more vulnerable to psychosocial stress. A study by Minkel et al. (Health Psychology, 2014) reported that the cortisol response to an acute stress situation was increased after sleep deprivation compared with a control condition indicating a more pronounced activation of the hypothalamic-pituitary-adrenal stress axis. I will also present recently collected data from young (18–30 years) and older (60–72 years) subjects that participated in four conditions (between subject design):

    (i) normal night sleep.

    (ii) normal night sleep & acute stress (Trier Social Stress Test).

    (iii) total sleep deprivation.

    (iv) total sleep deprivation & acute stress.

    The presentation thus provides state of the art knowledge of the link between sleep loss and vulnerability to stress.

  • 105.
    Schwarz, Johanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Gerhardsson, Andreas
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Stockholm University, Faculty of Social Sciences, Department of Psychology, Work and organizational psychology.
    van Leeuwen, Wessel
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Ericson, Mats
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Does sleep deprivation increase the vulnerability to acute psychosocial stress in young and older adults?2018In: Psychoneuroendocrinology, ISSN 0306-4530, E-ISSN 1873-3360, Vol. 96, p. 155-165Article in journal (Refereed)
    Abstract [en]

    Sleep loss and psychosocial stress often co-occur in today’s society, but there is limited knowledge on the combined effects. Therefore, this experimental study investigated whether one night of sleep deprivation affects the response to a psychosocial challenge. A second aim was to examine if older adults, who may be less affected by both sleep deprivation and stress, react differently than young adults. 124 young (18–30 years) and 94 older (60–72 years) healthy adults participated in one of four conditions: i. normal night sleep & Placebo-Trier Social Stress Test (TSST), ii. normal night sleep & Trier Social Stress Test, iii. sleep deprivation & Placebo-TSST, iv. sleep deprivation & TSST. Subjective stress ratings, heart rate variability (HRV), salivary alpha amylase (sAA) and cortisol were measured throughout the protocol. At the baseline pre-stress measurement, salivary cortisol and subjective stress values were higher in sleep deprived than in rested participants. However, the reactivity to and recovery from the TSST was not significantly different after sleep deprivation for any of the outcome measures. Older adults showed higher subjective stress, higher sAA and lower HRV at baseline, indicating increased basal autonomic activity. Cortisol trajectories and HRV slightly differed in older adults compared with younger adults (regardless of the TSST). Moreover, age did not moderate the effect of sleep deprivation. Taken together, the results show increased stress levels after sleep deprivation, but do not confirm the assumption that one night of sleep deprivation increases the responsivity to an acute psychosocial challenge.

  • 106. Söderström, Marie
    et al.
    Jeding, Kerstin
    Ekstedt, Mirjam
    Perski, Aleksander
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Insufficient Sleep Predicts Clinical Burnout2012In: Journal of Occupational Health Psychology, ISSN 1076-8998, E-ISSN 1939-1307, Vol. 17, no 2, p. 175-183Article in journal (Refereed)
    Abstract [en]

    The present prospective study aimed to identify risk factors for subsequent clinical burnout. Three hundred eighty-eight working individuals completed a baseline questionnaire regarding work stress, sleep, mood, health, and so forth. During a 2-year period, 15 subjects (7 women and 8 men) of the total sample were identified as "burnout cases," as they were assessed and referred to treatment for clinical burnout. Questionnaire data from the baseline measurement were used as independent variables in a series of logistic regression analyses to predict clinical burnout. The results identified "too little sleep (< 6 h)" as the main risk factor for burnout development, with adjustment for "work demands," "thoughts of work during leisure time," and "sleep quality." The first two factors were significant predictors in earlier steps of the multivariate regression. The results indicate that insufficient sleep, preoccupation with thoughts of work during leisure time, and high work demands are risk factors for subsequent burnout. The results suggest a chain of causation.

  • 107. Taillard, Jacques
    et al.
    Capelli, Aurore
    Sagaspe, Patricia
    Anund, Anna
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Philip, Pierre
    In-car nocturnal blue light exposure improves motorway driving: a randomized controlled trial2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 10, article id e46750Article in journal (Refereed)
    Abstract [en]

    Prolonged wakefulness greatly decreases nocturnal driving performance. The development of in-car countermeasures is a future challenge to prevent sleep-related accidents. The aim of this study is to determine whether continuous exposure to monochromatic light in the short wavelengths (blue light), placed on the dashboard, improves night-time driving performance. In this randomized, double-blind, placebo-controlled, cross-over study, 48 healthy male participants (aged 20-50 years) drove 400 km (250 miles) on motorway during night-time. They randomly and consecutively received either continuous blue light exposure (GOLite, Philips, 468 nm) during driving or 2*200 mg of caffeine or placebo of caffeine before and during the break. Treatments were separated by at least 1 week. The outcomes were number of inappropriate line crossings (ILC) and mean standard deviation of the lateral position (SDLP). Eight participants (17%) complained about dazzle during blue light exposure and were removed from the analysis. Results from the 40 remaining participants (mean age ± SD: 32.9±11.1) showed that countermeasures reduced the number of inappropriate line crossings (ILC) (F(2,91.11) = 6.64; p<0.05). Indeed, ILC were lower with coffee (12.51 [95% CI, 5.86 to 19.66], p = 0.001) and blue light (14.58 [CI, 8.75 to 22.58], p = 0.003) than with placebo (26.42 [CI, 19.90 to 33.71]). Similar results were found for SDLP. Treatments did not modify the quality, quantity and timing of 3 subsequent nocturnal sleep episodes. Despite a lesser tolerance, a non-inferior efficacy of continuous nocturnal blue light exposure compared with caffeine suggests that this in-car countermeasure, used occasionally, could be used to fight nocturnal sleepiness at the wheel in blue light-tolerant drivers, whatever their age. More studies are needed to determine the reproducibility of data and to verify if it can be generalized to women.

  • 108.
    Tamm, Sandra
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Cervenka, Simon
    Forsberg, Anton
    Estelius, Johanna
    Grunewald, Johan
    Gyllfors, Pär
    Karshikoff, Bianka
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kosek, Eva
    Lampa, Jon
    Lensmar, Catarina
    Strand, Victoria
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Halldin, Christer
    Ingvar, Martin
    Olgart Höglund, Caroline
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Evidence of fatigue, disordered sleep and peripheral inflammation, but not increased brain TSPO expression, in seasonal allergy: A [11C]PBR28 PET study2018In: Brain, behavior, and immunity, ISSN 0889-1591, E-ISSN 1090-2139, Vol. 68, p. 146-157Article in journal (Refereed)
    Abstract [en]

    Allergy is associated with non-specific symptoms such as fatigue, sleep problems and impaired cognition. One explanation could be that the allergic inflammatory state includes activation of immune cells in the brain, but this hypothesis has not been tested in humans. The aim of the present study was therefore to investigate seasonal changes in the glial cell marker translocator protein (TSPO), and to relate this to peripheral inflammation, fatigue and sleep, in allergy. We examined 18 patients with severe seasonal allergy, and 13 healthy subjects in and out-of pollen season using positron emission tomography (n = 15/13) and the TSPO radioligand [11C]PBR28. In addition, TNF-α, IL-5, IL-6, IL-8 and IFN-γ were measured in peripheral blood, and subjective ratings of fatigue and sleepiness as well as objective and subjective sleep were investigated. No difference in levels of TSPO was seen between patients and healthy subjects, nor in relation to pollen season. However, allergic subjects displayed both increased fatigue, sleepiness and increased percentage of deep sleep, as well as increased levels of IL-5 and TNF-α during pollen season, compared to healthy subjects. Allergic subjects also had shorter total sleep time, regardless of season. In conclusion, allergic subjects are indicated to respond to allergen exposure during pollen season with a clear pattern of behavioral disruption and peripheral inflammatory activation, but not with changes in brain TSPO levels. This underscores a need for development and use of more specific markers to understand brain consequences of peripheral inflammation that will be applicable in human subjects.

  • 109.
    Tamm, Sandra
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Nilsonne, Gustav
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    D'Onofrio, Paolo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Thuné, Hanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna F A
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Petrovic, P
    Fischer, H
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Effect of partial sleep deprivation on empathy for pain in an fMRI experiment.2014In: SFSS (Svensk Förening för Sömnforskning och Sömnmedicin) Årskongress 5-7 Maj 2014, Stockholm, Sweden, Stockholm: Svensk förening för sömnforskning och sömnmedicin , 2014Conference paper (Other academic)
  • 110.
    Tamm, Sandra
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Nilsonne, Gustav
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    D'Onofrio, Paolo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Thuné, Hanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Petrovic, P.
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Effect of partial sleep deprivation on empathy for pain in an fMRI experiment2014Conference paper (Other academic)
  • 111.
    Tamm, Sandra
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Nilsonne, Gustav
    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.
    Golkar, Armita
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology. Karolinska Institutet, Sweden.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Petrovic, Predrag
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Åkerstedt, Torbjörn
    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.
    Sleep restriction caused impaired emotional regulation without detectable brain activation changes—a functional magnetic resonance imaging study2019In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 6, no 3, article id 181704Article in journal (Refereed)
    Abstract [en]

    Sleep restriction has been proposed to cause impaired emotional processing and emotional regulation by inhibiting top-down control from prefrontal cortex to amygdala. Intentional emotional regulation after sleep restriction has, however, never been studied using brain imaging. We aimed here to investigate the effect of partial sleep restriction on emotional regulation through cognitive reappraisal. Forty-seven young (age 20–30) and 33 older (age 65–75) participants (38/23 with complete data and successful sleep intervention) performed a cognitive reappraisal task during fMRI after a night of normal sleep and after restricted sleep (3 h). Emotional downregulation was associated with significantly increased activity in the dorsolateral prefrontal cortex (pFWE < 0.05) and lateral orbital cortex (pFWE < 0.05) in young, but not in older subjects. Sleep restriction was associated with a decrease in self-reported regulation success to negative stimuli (p< 0.01) and a trend towards perceiving all stimuli as less negative (p = 0.07) in young participants. No effects of sleep restriction on brain activity nor connectivity were found in either age group. In conclusion, our data do not support the idea of a prefrontal-amygdala disconnect after sleep restriction, and neural mechanisms underlying behavioural effects on emotional regulation after insufficient sleep require further investigation.

  • 112.
    Tamm, Sandra
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Nilssone, Gustav
    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.
    Lamm, Claus
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud Universiteit, Netherlands.
    Petrovic, Predrag
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Biological psychology.
    Åkerstedt, Torbjörn
    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 sleep restriction on empathy for pain: An fMRI study in younger and older adults2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 12236Article in journal (Refereed)
    Abstract [en]

    Age and sleep both affect emotional functioning. Since sleep patterns change over the lifespan, we investigated the effects of short sleep and age on empathic responses. In a randomized cross-over experimental design, healthy young and older volunteers (n = 47 aged 20–30 years and n = 39 aged 65–75 years) underwent functional magnetic resonance imaging (fMRI) after normal sleep or night sleep restricted to 3 hours. During fMRI, participants viewed pictures of needles pricking a hand (pain) or Q-tips touching a hand (control), a well-established paradigm to investigate empathy for pain. There was no main effect of sleep restriction on empathy. However, age and sleep interacted so that sleep restriction caused increased unpleasantness in older but not in young participants. Irrespective of sleep condition, older participants showed increased activity in angular gyrus, superior temporal sulcus and temporo-parietal junction compared to young. Speculatively, this could indicate that the older individuals adopted a more cognitive approach in response to others’ pain. Our findings suggest that caution in generalizability across age groups is needed in further studies of sleep on social cognition and emotion.

  • 113. Theorell-Haglöw, Jenny
    et al.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna F. A.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Lindberg, Eva
    Predictors for Development of Excessive Daytime Sleepiness in Women: A Population-Based 10-Year Follow-Up2015In: Sleep, ISSN 0161-8105, E-ISSN 1550-9109, Vol. 38, no 12, p. 1995-2002Article in journal (Refereed)
    Abstract [en]

    Study Objectives:

    To analyze predictors of excessive daytime sleepiness (EDS) and to analyze how changes within risk factors over time predict incident EDS in women.

    Design:

    Population-based prospective study.

    Setting:

    General population of the City of Uppsala, Sweden.

    Participants:

    From a random, general population sample of 7,051 women from the Sleep and HEalth in women (“SHE”) cohort, 4,322 women without EDS at baseline were followed up after 10 y.

    Interventions:

    N/A.

    Measurements and Results:

    At baseline and follow-up, women answered a questionnaire on sleeping habits, somatic disease, obesity, insomnia, anxiety and depression, lifestyle, and social factors. The risk of incident EDS was analyzed from changes over time in risk factors using logistic regression modeling. Of the women, EDS developed in 7.9%. Incident: insomnia (adjusted odds ratio = 5.01; 95% confidence interval 3.63–6.92), anxiety and/or depression (3.34; 2.22–5.02), somatic disease (1.73; 1.17–2.55), obesity (1.91; 1.14–2.57), snoring (1.91; 1.17–3.10) and smoking (4.31; 1.95–9.54) were all independent risk factors for the development of EDS. In addition, persistent: insomnia (4.44; 2.97–6.65) and anxiety and/or depression (4.91; 3.17–7.62) increased the risk of developing EDS. Apart from incident: snoring and obesity, similar results were obtained when only including women without somatic disease in the analyses.

    Conclusion:

    Insomnia, anxiety and/or depression, and smoking were the most important factors for predicting incident excessive daytime sleepiness (EDS) and, in addition, somatic disease, obesity, and snoring predicted EDS. It is important not only to treat these conditions but also to inform women of the importance of a healthy lifestyle in order to prevent and reduce EDS in women.

  • 114. Thun, Eirunn
    et al.
    Bjorvatn, Bjørn
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Moen, Bente Elisabeth
    Waage, Siri
    Molde, Helge
    Pallesen, Ståle
    Trajectories of sleepiness and insomnia symptoms in Norwegian nurses with and without night work and rotational work2016In: Chronobiology International, ISSN 0742-0528, E-ISSN 1525-6073, Vol. 33, no 5, p. 480-489Article in journal (Refereed)
    Abstract [en]

    Numerous cross-sectional studies report high prevalence rates of sleepiness and insomnia in shift workers, but few longitudinal studies exist. We investigated trajectories of sleepiness and insomnia symptoms in a sample of Norwegian nurses across four measurements, spanning a total of four years (sleepiness) and five years (insomnia). The participants completed the Epworth Sleepiness Scale and the Bergen Insomnia Scale at each measurement instance. Latent growth curve models were used to analyse the data. Separate models examined night work (night work, entering and leaving night work) and rotational work (rotational work, entering and leaving rotational work) as predictors for trajectories of sleepiness and insomnia symptoms, respectively. Baseline values of sleepiness and insomnia were higher among rotational shift workers than among workers with fixed shifts (day or night). The results showed that night work throughout the period and entering night work during the period were not associated with different trajectories of sleepiness or insomnia symptoms, compared to not having night work. The same results were found for rotational work and entering rotational work, compared to not having rotational work. Leaving night work and leaving rotational work were associated with a decrease in sleepiness and insomnia symptoms, compared to staying in such work.

  • 115.
    Thuné, Hanna
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Nilsonne, Gustav
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Tamm, Sandra
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    D'Onofrio, Paolo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Schwarz, Johanna F A
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Effects of partial sleep deprivation on the neural mechanisms of face perception2014In: Journal of Sleep Research, Special issue: abstracts of the 22nd Congress of the European Sleep Research Society, 16–20 September 2014, Tallinn, Estonia, Chichester: Wiley-Blackwell, 2014, p. 245-Conference paper (Other academic)
  • 116.
    Tucker, Philip
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Bejerot, Eva E
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Aronsson, Gunnar
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Doctors' work schedules and work time control2013Conference paper (Refereed)
  • 117.
    Tucker, Philip
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Swansea University, United Kingdom.
    Bejerot, Eva
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud University, The Netherlands.
    Aronsson, Gunnar
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    The impact of work time control on physicians’ sleep and well-being2015In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 47, p. 109-116Article in journal (Refereed)
    Abstract [en]

    Physicians' work schedules are an important determinant of their own wellbeing and that of their patients. This study considers whether allowing physicians control over their work hours ameliorates the effects of demanding work schedules. A questionnaire was completed by hospital physicians regarding their work hours (exposure to long shifts, short inter-shift intervals, weekend duties, night duties, unpaid overtime; and work time control), sleep (quantity and disturbance) and wellbeing (burnout, stress and fatigue). Work time control moderated the negative impact that frequent night working had upon sleep quantity and sleep disturbance. For participants who never worked long shifts, work time control was associated with fewer short sleeps, but this was not the case for those who did work long shifts. Optimizing the balance between schedule flexibility and patient needs could enhance physicians' sleep when working the night shift, thereby reducing their levels of fatigue and enhancing patient care.

  • 118. Tucker, Philip
    et al.
    Brown, Menna
    Dahlgren, Anna
    Davies, Gwyneth
    Ebden, Philip
    Folkard, Simon
    Hutchings, Hayley
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    The impact of junior doctors' worktime arrangements on their fatigue and well-being2010In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 36, no 6, p. 458-465Article in journal (Refereed)
    Abstract [en]

    Objective Many doctors report working excessively demanding schedules that comply with the European Working Time Directive (EWTD). We compared groups of junior doctors working on different schedules in order to identify which features of schedule design most negatively affected their fatigue and well-being in recent weeks.

    Methods Completed by 336 doctors, the questionnaires focused on the respondents’ personal circumstances, work situation, work schedules, sleep, and perceptions of fatigue, work–life balance and psychological strain.

    Results Working 7 consecutive nights was associated with greater accumulated fatigue and greater work–life interference, compared with working just 3 or 4 nights. Having only 1 rest day after working nights was associated with increased fatigue. Working a weekend on-call between 2 consecutive working weeks was associated with increased work–life interference. Working frequent on-calls (either on weekends or during the week) was associated with increased work–life interference and psychological strain. Inter-shift intervals of <10 hours were associated with shorter periods of sleep and increased fatigue. The number of hours worked per week was positively associated with work–life interference and fatigue on night shifts.

    Conclusion The current findings identify parameters, in addition to those specified in the EWTD, for designing schedules that limit their impact on doctors’ fatigue and well-being.

  • 119. Vadeby, Anna
    et al.
    Forsman, Asa
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sandberg, David
    Anund, Anna
    Sleepiness and prediction of driver impairment in simulator studies using a Cox proportional hazard approach2010In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 42, no 3, p. 835-41Article in journal (Refereed)
    Abstract [en]

    Cox proportional hazard models were used to study relationships between the event that a driver is leaving the lane caused by sleepiness and different indicators of sleepiness. In order to elucidate different indicators' performance, five different models developed by Cox proportional hazard on a data set from a simulator study were used. The models consisted of physiological indicators and indicators from driving data both as stand alone and in combination. The different models were compared on two different data sets by means of sensitivity and specificity and the models' ability to predict lane departure was studied. In conclusion, a combination of blink indicators based on the ratio between blink amplitude and peak closing velocity of eyelid (A/PCV) (or blink amplitude and peak opening velocity of eyelid (A/POV)), standard deviation of lateral position and standard deviation of lateral acceleration relative road (ddy) was the most sensitive approach with sensitivity 0.80. This is also supported by the fact that driving data only shows the impairment of driving performance while blink data have a closer relation to sleepiness. Thus, an effective sleepiness warning system may be based on a combination of lane variability measures and variables related to eye movements (particularly slow eye closure) in order to have both high sensitivity (many correct warnings) and acceptable specificity (few false alarms).

  • 120.
    van Leeuwen, Wessel M A
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Barnett, M
    Peksan, C
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Long term sleep and fatigue at sea: a field study2014In: Journal of sleep research, Special issue: 22nd Congress of the European Sleep Research Society, 16-20 September 2014, Tallinn, Estonia, 2014Conference paper (Other academic)
  • 121.
    Watling, Christopher N.
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Queensland University of Technology, Australia.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud University, Netherlands.
    Anund, Anna
    Do repeated rumble strip hits improve driver alertness?2016In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 25, no 2, p. 241-247Article in journal (Refereed)
    Abstract [en]

    Driving while sleepy is associated with increased crash risk. Rumble strips are designed to alert a sleepy or inattentive driver when they deviate outside their driving lane. The current study sought to examine the effects of repeated rumble strip hits on levels of physiological and subjective sleepiness as well as simulated driving performance. In total, 36 regular shift workers drove a high-fidelity moving base simulator on a simulated road with rumble strips installed at the shoulder and centre line after a working a full night shift. The results show that, on average, the first rumble strip occurred after 20 min of driving, with subsequent hits occurring 10 min later, with the last three occurring approximately every 5 min thereafter. Specifically, it was found that the first rumble strip hit reduced physiological sleepiness; however, subsequent hits did not increase alertness. Moreover, the results also demonstrate that increased subjective sleepiness levels, via the Karolinska Sleepiness Scale, were associated with a greater probability of hitting a rumble strip. The present results suggest that sleepiness is very resilient to even strongly arousing stimuli, with physiological and subjective sleepiness increasing over the duration of the drive, despite the interference caused by rumble strips.

  • 122. Westerlund, Anna
    et al.
    Bellocco, Rino
    Sundström, Johan
    Adami, Hans-Olov
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Trolle Lagerros, Ylva
    Sleep characteristics and cardiovascular events in a large Swedish cohort2013In: European Journal of Epidemiology, ISSN 0393-2990, E-ISSN 1573-7284, Vol. 28, no 6, p. 463-473Article in journal (Refereed)
    Abstract [en]

    Limited evidence suggests that the association between sleep duration and cardiovascular events is strongest in individuals who also report sleep disturbances. We investigated sleep duration and insomnia symptoms in relation to incident cardiovascular events in the Swedish National March Cohort comprising 41,192 adults. Habitual sleep duration and difficulty falling asleep, difficulty maintaining sleep, early morning awakening, and nonrestorative sleep were self-reported in 1997. During 13.2 years of follow-up, we identified 4,031 events (myocardial infarction, stroke, heart failure, or death from cardiovascular disease) in the Swedish National Patient Register and the Cause of Death Register. After adjustment for potential confounders, short sleep duration (≤5 h) was associated with slightly increased risks of overall cardiovascular events and, specifically, myocardial infarction: hazard ratio, HR (95 % confidence interval) 1.24 (1.06-1.44) and 1.42 (1.15-1.76), respectively. These HRs were attenuated as we included BMI, depressive symptoms and other relevant covariates in our analysis. Insomnia symptoms per se were unrelated to risk. However, in a joint analysis, there was some evidence that short sleepers who reported frequent insomnia symptoms had the highest HRs (1.26-1.39) of overall cardiovascular events. Short sleep or insomnia symptoms without the other conferred no increased risk. Our results suggest that symptoms of sleep disturbance should be taken into account when assessing the association between short sleep and cardiovascular disease.

  • 123. Westerlund, Anna
    et al.
    Bottai, Matteo
    Adami, Hans-Olov
    Bellocco, Rino
    Nyrén, Olof
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Lagerros, Ylva Trolle
    Habitual sleep patterns and the distribution of body mass index: cross-sectional findings among Swedish men and women.2014In: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 15, no 10, p. 1196-1203Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To compare distributions of body mass index (BMI) between individuals with different habitual sleep patterns.

    METHODS: We performed cross-sectional analyses of 40,197 Swedish adults (64% women), who reported sleep duration and quality, weight, height, and possible confounding factors in 1997. Using quantile regression, we estimated associations between sleep patterns and selected percentiles of the distribution of BMI.

    RESULTS: While the medians were similar, larger adjusted values of BMI were estimated in the upper part of the distribution among men and women with short sleep (≤5 h) compared with medium-length sleep (6-8 h). For example, in men, the 90th percentile of BMI was 0.80 kg/m(2) (95% confidence interval: 0.17-1.43 kg/m(2)) higher among short sleepers. In women, long sleepers (≥9 h) also showed larger values in the upper part of the BMI distribution; the 90th percentile was 1.23 kg/m(2) (0.42-2.04 kg/m(2)) higher than in medium-length sleepers. In male long sleepers, smaller values were estimated in the lower part of the BMI distribution; the 10th percentile was 0.84 kg/m(2) lower (0.35-1.32 kg/m(2)) than in medium-length sleepers. The 90th percentile of BMI in women with poor-quality compared with good-quality sleep was larger by 0.82 kg/m(2) (0.47-1.16 kg/m(2)); the 10th percentile was smaller by 0.17 kg/m(2) (0.02-0.32 kg/m(2)).

    CONCLUSIONS: Short, long or poor-quality sleepers showed larger, or smaller, values at the tails of the BMI distribution, but similar medians. Hence, unfavorable sleep patterns and BMI were associated only in a subset of this study population.

  • 124. Westerlund, Anna
    et al.
    Brandt, Lena
    Harlid, Richard
    Åkerstedt, Torbjorn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Lagerros, Ylva Trolle
    Using the Karolinska Sleep Questionnaire to identify obstructive sleep apnea syndrome in a sleep clinic population2014In: Clinical Respiratory Journal, ISSN 1752-6981, E-ISSN 1752-699X, Vol. 8, no 4, p. 444-454Article in journal (Refereed)
    Abstract [en]

    Introduction: In Scandinavia, portable monitoring has virtually replaced standard polysomnography for diagnosis of obstructive sleep apnea syndrome (OSAS). Because waiting times for specialized OSAS care remain long, an accurate screening tool to exclude low-risk patients from diagnostic testing would be valuable. Objectives: To examine the diagnostic accuracy of the Karolinska Sleep Questionnaire (KSQ) for OSAS. Methods: Consecutive patients, 30-66 years old, attending a large sleep clinic in Sweden for OSAS evaluation completed the KSQ and underwent in-home portable monitoring and medical history evaluation. OSAS was defined as apnea-hypopnea index >= 5 with symptoms of disease. We calculated sensitivity and specificity of apnea/snoring and sleepiness indices of the KSQ. Retrospectively, we combined six KSQ items (snoring, breathing cessations, disturbed sleep, etc.) and four clinical variables (age, sex, body mass index, smoking status) predictive of OSAS into a new instrument, which we also evaluated. Instrument score ranged between 0 and 21; a higher score indicated more severe symptoms. Results: Of 103 patients, 62 were diagnosed with OSAS. Sensitivity and specificity of the indices were 0.56 and 0.68 (apnea/snoring), and 0.37 and 0.71 (sleepiness). The new instrument performed optimally at a score of 9. Sensitivity was 0.76 (95% confidence interval 0.63-0.86) and specificity 0.88 (0.74-0.96). Between 19.4% and 50.5% of patients were unaware of having apnea/snoring symptoms. Conclusions: Diagnostic accuracy of the apnea/snoring and sleepiness indices for OSAS was poor but could be improved by combining clinical and KSQ items. The usefulness of the apnea/snoring index and the combined instrument was questionable because of extensive symptom unawareness.

  • 125. Westerlund, Anna
    et al.
    Trolle Lagerros, Ylva
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud University, The Netherlands; Karolinska Institutet, Sweden.
    Axelsson, John
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Relationships Between Questionnaire Ratings of Sleep Quality and Polysomnography in Healthy Adults2016In: Behavioural Sleep Medicine, ISSN 1540-2002, E-ISSN 1540-2010, Vol. 14, no 2, p. 185-199Article in journal (Refereed)
    Abstract [en]

    This study aimed to examine the association between polysomnographic sleep and subjective habitual sleep quality and restoration from sleep. Thirty-one normal sleepers completed the Karolinska Sleep Questionnaire and multiple home polysomnography recordings (n = 2-5). Using linear regression, sleep quality and restoration were separately analyzed as functions of standard polysomnography parameters: sleep efficiency, total sleep time, sleep latency, stage 1 and 2 sleep, slow-wave sleep, rapid eye movement sleep, wake time after sleep onset, and awakenings (n), averaged across recordings. Stage 2 and slow-wave sleep predicted worse and better sleep quality, respectively. Also, slow-wave sleep predicted less subjective restoration, although adjustment for age attenuated this relation. Our findings lend some physiological validity to ratings of habitual sleep quality in normal sleepers. Data were less supportive of a physiological correlate of ratings of restoration from sleep.

  • 126. Åkerstedt Miley, Anna
    et al.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Comparing two versions of the Karolinska Sleepiness Scale (KSS)2016In: Sleep and Biological Rhythms, ISSN 1446-9235, E-ISSN 1479-8425, Vol. 14, no 3, p. 257-260Article in journal (Refereed)
    Abstract [en]

    The Karolinska Sleepiness Scale (KSS) is frequently used to study sleepiness in various contexts. However, it exists in two versions, one with labels on every other step (version A), and one with labels on every step (version B) on the 9-point scale. To date, there are no studies examining whether these versions can be used interchangeably. The two versions were here compared in a 24 hr wakefulness study of 12 adults. KSS ratings were obtained every hour, alternating version A and B. Results indicated that the two versions are highly correlated, do not have different response distributions on labeled and unlabeled steps, and that the distributions across all steps have a high level of correspondence (Kappa = 0.73). It was concluded that the two versions are quite similar.

  • 127.
    Åkerstedt, Torbjorn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Schwarz, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Gruber, Georg
    Theorell-Haglöw, Jenny
    Lindberg, Eva
    Short sleep-poor sleep? A polysomnographic study in a large population-based sample of women2019In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 28, no 4, article id e12812Article in journal (Refereed)
    Abstract [en]

    There is a lack of studies on the association between total sleep time (TST) and other polysomnographical parameters. A key question is whether a short sleep is an expression of habitual short sleep, or whether it reflects temporary impairment. The purpose of the present study was to investigate the association between TST and amount of sleep stages and sleep continuity measures, in a large population-based sample of women (n = 385), sleeping at home in a normal daily life setting. The results show that sleep efficiency, N1 (min), N2 (min), REM (min), REM% and proportion of long sleep segments, increased with increasing TST, whereas the number of awakenings/hr, the number of arousals/hr, N1% and REM intensity decreased. In addition, longer sleep was more associated with TST being perceived as of usual duration and with better subjective sleep quality. TST was not associated with habitual reported sleep duration. It was concluded that short TST of a recorded sleep in a real-life context may be an indicator of poor objective sleep quality for that particular sleep episode. Because individuals clearly perceived this reduction, it appears that self-reports of poor sleep quality often may be seen as indicators of poor sleep quality. It is also concluded that PSG-recorded sleep duration does not reflect habitual reported sleep duration in the present real-life context.

  • 128.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Arbete som stör dygnsrytmen2008In: Arbetslivsfysiologi, Studentlitteratur, Lund , 2008, p. 279-306Chapter in book (Other (popular science, discussion, etc.))
  • 129.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Occupational Impact2013In: Encyclopedia of Sleep / [ed] Clete Kushida, Academic Press, 2013, p. 308-310Chapter in book (Refereed)
    Abstract [en]

    Occupational impact on sleep is mostly associated with psychosocial factors. In particular, high work demands (stress) lead to increased activation, which causes difficulties initiating or maintaining sleep. At severe levels, characterized by preoccupation with the work situation, sleep is strongly affected and may in the long run lead to burnout, with very poor sleep (far beyond that of the insomniac) and extreme exhaustion. Physical work factors seem to have only marginal effects on sleep.

  • 130.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Social and Economic Impact2013In: Encyclopedia of Sleep / [ed] Clete Kushida, Academic Press, 2013, p. 306-307Chapter in book (Refereed)
    Abstract [en]

    Social factors influence sleep. Socioeconomic status (SES) may be the most important factor, with longer and better sleep among higher SES groups. The reasons may be related to income, education, healthier lifestyles and several other issues. Social support is a strong predictor of good sleep. Also race is related to sleep, with better sleep among whites. SES is of importance here, but unfair treatment is also important. Sleep also deteriorates with increasing age, but alertness increases. Women report more sleep problems than men but sleep is physiologically better. Singles in general show more sleep complaints, which may be related to unhealthy lifestyles and to some extent to social isolation.

  • 131.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sömnen2012In: Hjärnan / [ed] Lars Olson och Anna Josephson, Solna: Karolinska Institutet University Press , 2012, 2, p. 145-161Chapter in book (Refereed)
  • 132.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Återhämtning och sömn2012In: Psykosocial miljö och stress / [ed] Töres Theorell, Lund: Studentlitteratur , 2012, 2, p. 81-90Chapter in book (Other academic)
  • 133.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Alfredsson, L
    Westerholm, P
    Fischer, H
    Nilsson, L-G
    Nordin, M
    Fatigue/sleepiness and important aspects of sleep restoration improve across aging2014Conference paper (Other academic)
  • 134.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet.
    Anund, Anna
    Axelsson, John
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Subjective sleepiness is a sensitive indicator of insufficient sleep and impaired waking function2014In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 23, no 3, p. 240-252Article in journal (Refereed)
    Abstract [en]

    The main consequence of insufficient sleep is sleepiness. While measures of sleep latency, continuous encephalographical/electro-oculographical (EEG/EOG) recording and performance tests are useful indicators of sleepiness in the laboratory and clinic, they are not easily implemented in large, real-life field studies. Subjective ratings of sleepiness, which are easily applied and unobtrusive, are an alternative, but whether they measure sleepiness sensitively, reliably and validly remains uncertain. This review brings together research relevant to these issues. It is focused on the Karolinska Sleepiness Scale (KSS), which is a nine-point Likert-type scale. The diurnal pattern of sleepiness is U-shaped, with high KSS values in the morning and late evening, and with great stability across years. KSS values increase sensitively during acute total and repeated partial sleep deprivation and night work, including night driving. The effect sizes range between 1.5 and 3. The relation to driving performance or EEG/EOG indicators of sleepiness is highly significant, strongly curvilinear and consistent across individuals. High (>6) KSS values are associated particularly with impaired driving performance and sleep intrusions in the EEG. KSS values are also increased in many clinical conditions such as sleep apnea, depression and burnout. The context has a strong influence on KSS ratings. Thus, physical activity, social interaction and light exposure will reduce KSS values by 1-2 units. In contrast, time-on-task in a monotonous context will increase KSS values by 1-2 units. In summary, subjective ratings of sleepiness as described here is as sensitive and valid an indicator of sleepiness as objective measures, and particularly suitable for field studies.

  • 135.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Individual validation of model predictions of sleepiness and sleep hours2007In: Somnologie, Vol. 11, p. 169-174Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Several mathematical models for prediction of sleepiness have been developed. Few validations on individual levels are available.

    Background

    The present study was designed to provide validation on the individual level of predictions using the Three Process-Model of alertness regulation. Model predictions of sleep timing were also tested.

    Method

    Sixteen shift workers participated in the study. Ratings of sleepiness were made every 2h across three shifts. The model was used to predict empirical ratings using as input only information of beginning and end of work shifts, as well as using information on sleep from actigraphs (in a separate analysis).

    Results

    The prediction using only information on work shifts correlated r=0.55 (p<0.001) with empirical ratings. Predictions were generally within ±1 confidence interval of the ratings. Adding actigraphy sleep data improved predictions marginally. The model predictions of onset and offset of sleep were generally close to the target.

    Conclusion

    It was concluded that model predictions have a rather high validity both with respect to sleepiness and to sleep timing. It is probable that other information on individual differences will further improve predictability.

  • 136.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Orsini, Nicola
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Do sleep, stress, and illness explain daily variations in fatigue?: A prospective study2014In: Journal of Psychosomatic Research, ISSN 0022-3999, E-ISSN 1879-1360, Vol. 76, no 4, p. 280-285Article in journal (Refereed)
    Abstract [en]

    Objective: Fatigue is related to a number of serious diseases, as well as to general well-being. It is also a major cause of sickness absence and use of health facilities. Still, the determinants of variations in fatigue are little investigated. The purpose of present study was to investigate the relationships between the daily variations of fatigue with sleep during the previous night, stress or disease symptoms during the same day - across 42 consecutive days of normal life. Methods: 50 individuals participated and gave diary reports and used an actigraph across the 42 days. The data was analyzed using a multilevel approach with mixed model regression. Results: The analyses showed that the day-to-day variation in fatigue was related to (poor) sleep quality (p < .001) and (reduced) sleep duration (p < .01) the previous night, as well as to higher stress (p < .05), and to the occurrence of a cold or fever (p < .001) during the same day as the fatigue rating. Fatigue was also strongly related to poorer subjective health (p < .001) and sleepiness (p < .001) during the same day. Conclusion: The results indicate that prior sleep (and sleepiness) as well as stress and illness are consistently connected to how fatigue is experienced during normal living conditions.

  • 137.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Lekander, Mats
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Orsini, Nicola
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    The daily variation in sleepiness and its relation to the preceding sleep episode - a prospective study across 42days of normal living2013In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 22, no 3, p. 258-265Article in journal (Refereed)
    Abstract [en]

    Sleepiness is linked to accidents and reduced performance, and is usually attributed to short/poor prior sleep and sleepiness. However, while the link between reduced sleep and subsequent sleepiness is well established in laboratory experiments of sleep reduction, very little is known about the day-to-day variation of sleepiness in everyday life and its relation to the immediately preceding sleep episode. The purpose of the present study was to investigate the characteristics of this relation across 42 consecutive days. Fifty volunteers participated. Self-reports of sleep were given in the morning and recorded with actigraphy; health was rated in the evening; and sleepiness was rated at eight points during the day (on a scale of 1-9). Results from mixed-model regression analyses showed that, on average, total sleep time predicted sleepiness during the rest of the day across the 42 days, with sleepiness increasing with shorter preceding sleep (β = -0.15 units h(-1) , P < 0.001). Sleepiness also increased with earlier time of rising and lower-rated sleep quality. Days off reduced sleepiness, but was accounted for by sleep. Self-rated health improved when sleepiness was low during the same day (β = -0.36 unit unit(-1) of rated health, P < 0.001), but the two were measured simultaneously. Napping was related to high sleepiness during the same day. Actigraphy measures of sleep duration showed similar, but somewhat weaker, effects than diary measures. It was concluded that the main determinants of daytime sleepiness in a real-life day-to-day context were short sleep, poor sleep and early rising, and that days with high sleepiness ended with ratings of poorer health.

  • 138.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Discacciati, Andrea
    Miley-Åkerstedt, Anna
    Westerlund, Hugo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Aging and the Change in Fatigue and Sleep - A Longitudinal Study Across 8 Years in Three Age Groups2018In: Frontiers in Psychology, ISSN 1664-1078, E-ISSN 1664-1078, Vol. 9, article id 234Article in journal (Refereed)
    Abstract [en]

    Fatigue is prevalent in the population and usually linked to sleep problems, and both are related to age. However, previous studies have been cross-sectional. The purpose of the present study was to investigate the trajectories of sleep and fatigue across 8 years of aging in a large group (N > 8.000) of individuals. A second purpose was to investigate whether fatigue trajectories would differ between age groups, and whether different trajectories of fatigue would be reflected in a corresponding difference in trajectories for sleep variables. Results from mixed model analyses showed that fatigue decreased across 8 years in all age groups, while sleep problems increased, non-restorative sleep decreased, weekend sleep duration decreased, and weekday sleep duration showed different patterns depending on age. Furthermore, the larger the decrease in fatigue, the larger was the increase in sleep duration across years, the lower was the increase of sleep problems, and the larger was the decrease of non-restorative sleep. The results suggest that aging has positive effects on fatigue and sleep and that these changes are linked.

  • 139.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Garefelt, Johanna
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Richter, Anne
    Stockholm University, Faculty of Social Sciences, Department of Psychology. Karolinska Institutet, Sweden.
    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. North West University, South Africa.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Work and Sleep - A Prospective Study of Psychosocial Work Factors, Physical Work Factors, and Work Scheduling2015In: Sleep, ISSN 0161-8105, E-ISSN 1550-9109, Vol. 38, no 7, p. 1129-1136Article in journal (Refereed)
    Abstract [en]

    Study Objectives: There is limited knowledge about the prospective relationship between major work characteristics (psychosocial, physical, scheduling) and disturbed sleep. The current study sought to provide such knowledge. Design: Prospective cohort, with measurements on two occasions (T1 and T2) separated by two years. Setting: Naturalistic study, Sweden. Participants: There were 4,827 participants forming a representative sample of the working population. Measurements and Results: Questionnaire data on work factors obtained on two occasions were analyzed with structural equation modeling. Competing models were compared in order to investigate temporal relationships. A reciprocal model was found to fit the data best. Sleep disturbances at T2 were predicted by higher work demands at T1 and by lower perceived stress at T1. In addition, sleep disturbances at T1 predicted subsequent higher perception of stress, higher work demands, lower degree of control, and less social support at work at T2. A cross-sectional mediation analysis showed that (higher) perceived stress mediated the relationship between (higher) work demands and sleep disturbances; however, no such association was found longitudinally. Conclusions: Higher work demands predicted disturbed sleep, whereas physical work characteristics, shift work, and overtime did not. In addition, disturbed sleep predicted subsequent higher work demands, perceived stress, less social support, and lower degree of control. The results suggest that remedial interventions against sleep disturbances should focus on psychosocial factors, and that such remedial interventions may improve the psychosocial work situation in the long run.

  • 140.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Ghilotti, Francesca
    Grotta, Alessandra
    Stockholm University, Faculty of Social Sciences, Centre for Health Equity Studies (CHESS). Karolinska Institutet, Sweden.
    Bellavia, Andrea
    Trolle Lagerros, Ylva
    Bellocco, Rino
    Sleep duration, mortality and the influence of age2017In: European Journal of Epidemiology, ISSN 0393-2990, E-ISSN 1573-7284, Vol. 32, no 10, p. 881-891Article in journal (Refereed)
    Abstract [en]

    Prior work has shown that both short and long sleep predict mortality. However, sleep duration decreases with age and this may affect the relationship of sleep duration with mortality. The purpose of the present study was to assess whether the association between sleep duration and mortality varies with age. Prospective cohort study. 43,863 individuals (64% women), recruited in September 1997 during the Swedish National March and followed through record-linkages for 13 years. Sleep duration was self-reported and measured using the Karolinska Sleep Questionnaire, and grouped into 4 categories: ae5, 6, 7 (reference) and 8 h. Up to 2010 3548 deaths occurred. Multivariable Cox proportional hazards regression models with attained age as time scale were fitted to estimate mortality rate ratios. Among individuals < 65 years, short (ae5 h) and long (8 h) sleep duration showed a significant relationship with mortality (HR 1.37, 95% CI 1.09-1.71, and HR 1.27, 95% CI 1.08-1.48). Among individuals 65 years or older, no relationships between sleep duration and mortality were observed. The effect of short and long sleep duration on mortality was highest among young individuals and decreased with increasing age. The results suggest that age plays an important role in the relationship between sleep duration and mortality.

  • 141.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Ghilotti, Francesca
    Grotta, Alessandra
    Stockholm University, Faculty of Social Sciences, Centre for Health Equity Studies (CHESS). Karolinska Institutet, Sweden.
    Zhao, Hongwei
    Adami, Hans-Olov
    Trolle-Lagerros, Ylva
    Bellocco, Rino
    Sleep duration and mortality - Does weekend sleep matter?2019In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 28, no 1, article id e12712Article in journal (Refereed)
    Abstract [en]

    Previous studies have found a U-shaped relationship between mortality and (weekday) sleep duration. We here address the association of both weekday and weekend sleep duration with overall mortality. A cohort of 43,880 subjects was followed for 13 years through record-linkages. Cox proportional hazards regression models with attained age as time-scale were fitted to estimate multivariable-adjusted hazard ratios and 95% confidence intervals for mortality; stratified analyses on age (<65 years, >= 65 years) were conducted. Among individuals <65 years old, short sleep (<= 5 hr) during weekends at baseline was associated with a 52% higher mortality rate (hazard ratios 1.52; 95% confidence intervals 1.15-2.02) compared with the reference group (7 hr), while no association was observed for long (>= 9 hr) weekend sleep. When, instead, different combinations of weekday and weekend sleep durations were analysed, we observed a detrimental association with consistently sleeping <= 5 hr (hazard ratios 1.65; 95% confidence intervals 1.22-2.23) or >= 8 hr (hazard ratios 1.25; 95% confidence intervals 1.05-1.50), compared with consistently sleeping 6-7 hr per day (reference). The mortality rate among participants with short sleep during weekdays, but long sleep during weekends, did not differ from the rate of the reference group. Among individuals >= 65 years old, no association between weekend sleep or weekday/weekend sleep durations and mortality was observed. In conclusion, short, but not long, weekend sleep was associated with an increased mortality in subjects <65 years. In the same age group, short sleep (or long sleep) on both weekdays and weekend showed increased mortality. Possibly, long weekend sleep may compensate for short weekday sleep.

  • 142.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Hallvig, David
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Normative data on the diurnal pattern of the Karolinska Sleepiness Scale ratings and its relation to age, sex, work, stress, sleep quality and sickness absence/illness in a large sample of daytime workers2017In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 26, no 5, p. 559-566Article in journal (Refereed)
    Abstract [en]

    Self-rated sleepiness responds to sleep loss, time of day and work schedules. There is, however, a lack of a normative reference showing the diurnal pattern during a normal working day, compared with a day off, as well as differences depending on stress, sleep quality, sex, age and being sick listed. The present study sought to provide such data for the Karolinska Sleepiness Scale. Participants were 431 individuals working in medium-sized public service units. Sleepiness (Karolinska Sleepiness Scale, scale 1-9) was rated at six times a day for a working week and 2 days off (>90.000 ratings). The results show a clear circadian pattern, with high values during the morning (4.5 at 07:00 hours) and evening (6.0 at 22:00 hours), and with low values (3-4) during the 10:0016: 00 hours span. Women had significantly higher (0.5 units) Karolinska Sleepiness Scale values than men, as did younger individuals (0.3 units), those with stress (1.3 units above the low-stress group) and those with poor sleep quality (1.0 units above those with qood sleep quality). Days off showed reduced sleepiness (0.7 units), while being sick listed was associated with an increased sleepiness (0.8 units). Multiple regression analysis of mean sleepiness during the working week yielded mean daytime stress, mean sleep quality, age, and sex as predictors (not sleep duration). Improved sleep quality accounted for the reduced sleepiness during days off, but reduced stress was a second factor. Similar results were obtained in a longitudinal mixed-model regression analysis across the 7 days of the week. The percentage of ratings at Karolinska Sleepiness Scale risk levels (8 + 9) was 6.6%, but most of these were obtained at 22:00 hours. It was concluded that sleepiness ratings are strongly associated with time of day, sleep quality, stress, work day/day off, being ill, age, and sex.

  • 143.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Ingre, Michael
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Anund, Anna
    Sandberg, David
    Wahde, Mattias
    Philip, Pierre
    Kronberg, Peter
    Reaction of sleepiness indicators to partial sleep deprivation, time of day and time on task in a driving simulator - the DROWSI project2010In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 19, no 2, p. 298-309Article in journal (Refereed)
    Abstract [en]

    Studies of driving and sleepiness indicators have mainly focused on prior sleep reduction. The present study sought to identify sleepiness indicators responsive to several potential regulators of sleepiness: sleep loss, time of day (TOD) and time on task (TOT) during simulator driving. Thirteen subjects drove a high-fidelity moving base simulator in six 1-h sessions across a 24-h period, after normal sleep duration (8 h) and after partial sleep deprivation (PSD; 4 h). The results showed clear main effects of TOD (night) and TOT but not for PSD, although the latter strongly interacted with TOD. The most sensitive variable was subjective sleepiness, the standard deviation of lateral position (SDLAT) and measures of eye closure [duration, speed (slow), amplitude (low)]. Measures of electroencephalography and line crossings (LCs) showed only modest responses. For most variables individual differences vastly exceeded those of the fixed effects, except for subjective sleepiness and SDLAT. In a multiple regression analysis, SDLAT, amplitude/peak eye-lid closing velocity and blink duration predicted subjective sleepiness bouts with a sensitivity and specificity of about 70%, but were mutually redundant. The prediction of LCs gave considerably weaker, but similar results. In summary, SDLAT and eye closure variables could be candidates for use in sleepiness-monitoring devices. However, individual differences are considerable and there is need for research on how to identify and predict individual differences in susceptibility to sleepiness.

  • 144.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Sleep, Work, and Occupational Stress2012In: The Oxford Handbook of Sleep and Sleep disorders / [ed] Charles M. Morin, Colin Espie, New York: Oxford University Press , 2012, p. 248-265Chapter in book (Refereed)
  • 145.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Säkerhet, arbetstider och trötthet2013In: Patientsäkerhet: teori och praktik / [ed] Synnöve Ödegård, Stockholm: Liber, 2013Chapter in book (Other academic)
  • 146.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    What work schedule characteristics constitute a problem to the individual? A representative study of Swedish shift workers2017In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 59, p. 320-325Article in journal (Refereed)
    Abstract [en]

    The purpose was to investigate which detailed characteristics of shift schedules that are seen as problems to those exposed. A representative national sample of non-day workers (N = 2031) in Sweden was asked whether they had each of a number of particular work schedule characteristics and, if yes, to what extent this constituted a "big problem in life". It was also inquired whether the individual's work schedules had negative consequences for fatigue, sleep and social life. The characteristic with the highest percentage reporting a big problem was "short notice (<1 month) of a new work schedule" (30.5%), <11 h off between shifts (27.8%), and split duty (>1.5 h break at mid-shift, 27.2%). Overtime (>10 h/week), night work, morning work, day/night shifts showed lower prevalences of being a "big problem". Women indicated more problems in general. Short notice was mainly related to negative social effects, while <11 h off between shifts was related to disturbed sleep, fatigue and social difficulties. It was concluded that schedules involving unpredictable working hours (short notice), short daily rest between shifts, and split duty shifts constitute big problems. The results challenge current views of what aspects of shift work need improvement, and negative social consequences seem more important than those related to health.

  • 147.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Impaired sleep after bedtime stress and worries.2007In: Biol Psychol, ISSN 0301-0511, Vol. 76, no 3, p. 170-3Article in journal (Other academic)
    Abstract [en]

    Akerstedt T, Kecklund G, Axelsson J.

    torbjorn.akerstedt@stressforskning.su.se

    Stress is assumed to impair sleep, but there is very little empirical evidence for this using sleep recordings. Here, we recorded sleep (at home) in 33 normal participants on three nights, which followed days with low, high and intermediate stress. The participants made daily ratings of the level of stress/worries at bedtime and also two-hourly ratings of stress. Only those 16 individuals who differed in stress/worries between two nights were analysed. There was a significantly lower sleep efficiency (81.0% versus 85.2%) a higher percent Wake (22.6% versus 15.6%) and a longer latency to Stage 3 (33.9 versus 18.3 min) during the nights with a higher stress/worry bedtime rating. None of the other sleep variables were affected. Also mean daytime stress ratings were significantly higher on the day preceding and following the high stress/worries sleep. It was concluded that moderate increases in stress/worries at bedtime are associated with moderately impaired sleep.

    PMID: 17884278 [PubMed - in process]

  • 148.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Axelsson, John
    Subjective and objectiv quality of sleep2008In: Somnologie, ISSN 1432-9123, E-ISSN 1439-054X, Vol. 12, p. 104-109Article in journal (Other academic)
    Abstract [en]

    Relatively few studies have tried to relate subjective sleep quality to objective sleep parameters and most have been carried out in laboratory settings and often with patients and usually only for a single night. The present study used a group of 33 subjects who had sleep polysomnographically recorded in their homes for three nights during a period of several weeks. First a multiple regression analysis was carried out for each night with a 4-item sleep quality index as the dependent variable and conventional sleep parameters as predictors. This yielded a significant beta value for percent Stage O for each of the three nights. Sleep efficiency showed a significant correlation with sleep quality for two nights but did not enter the regression. When the night with the best and poorest sleep were compared, the only significant variable became percent SWS. It was suggested that the differing results may have been due to the large age span confusing SWS/quality correlations.

  • 149.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Selén, Jan
    Disturbed sleep and fatigue as predictors of return from long-term sickness absence2010In: Industrial Health, ISSN 0019-8366, E-ISSN 1880-8026, Vol. 48, no 2, p. 209-14Article in journal (Refereed)
    Abstract [en]

    Long-term sickness absence has doubled in Sweden, as has complaints of disturbed sleep. The present study sought to investigate the prospective link between long-term sickness absence and disturbed sleep or fatigue. Sleep and fatigue from a representative national sample was followed up 1.5-2 yr later in terms of return from long-term (>or=90 d) and intermediate term (14-89 d) sickness absence. 8,300 individuals participated in the survey, out of which 372 were on long-term and 1,423 were on intermediate term sick leave. The data was analyzed using logistic regression analysis with adjustment for background and work environment variables. Separate analyses were carried out for disturbed sleep and fatigue since they were correlated. The results showed that those with disturbed sleep at the start had an Odds Ratio (OR) of 0.56 (95% Confidence Interval (CI)=0.35-0.90) for returning from long-term sickness absence. For fatigue the results were OR=0.56 (CI=0.34-0.90). Intermediate term sickness absence showed similar, but slightly weaker, results. The results indicate that disturbed sleep and fatigue are predictors of lack of return from long term and intermediate term sickness absence.

  • 150.
    Åkerstedt, Torbjörn
    et al.
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institutet, Sweden.
    Knutsson, Anders
    Narusyte, Jurgita
    Svedberg, Pia
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Radboud University Nijmegen, Netherlands.
    Alexanderson, Kristina
    Night work and breast cancer in women: a Swedish cohort study2015In: BMJ Open, ISSN 2044-6055, E-ISSN 2044-6055, Vol. 5, no 4, article id e008127Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: Recent research has suggested a moderate link between night work and breast cancer in women, mainly through case-control studies, but non-significant studies are also common and cohort studies are few. The purpose of the present study was to provide new information from cohort data through investigating the association between the number of years with night work and breast cancer among women.

    DESIGN: Cohort study of individuals exposed to night shift work in relation to incidence of breast cancer in women.

    SETTING: Individuals in the Swedish Twin registry, with follow-up in the Swedish Cancer Registry.

    PARTICIPANTS: 13 656 women from the Swedish Twin Registry, with 3404 exposed to night work.

    OUTCOME MEASURES: Breast cancer from the Swedish Cancer Registry (463 cases) during a follow-up time of 12 years.

    RESULTS: A Cox proportional hazards regression analysis with control for a large number of confounders showed that the HR was HR=1.68 (95% CI 0.98 to 2.88) for the group with >20 years of night work. When the follow-up time was limited to ages below 60 years, those exposed >20 years showed a HR=1.77 (95% CI 1.03 to 3.04). Shorter exposure to night work showed no significant effects.

    CONCLUSIONS: The present results, together with previous work, suggest that night work is associated with an increased risk of breast cancer in women, but only after relatively long-term exposure.

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