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  • 151. Xiong, Ying
    et al.
    Tvedt, Jonas
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Psykobiologi och epidemiologi.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Psykobiologi och epidemiologi. Karolinska Institutet, Sweden.
    Cadar, Dorina
    Wang, Hui-Xin
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Psykobiologi och epidemiologi.
    Impact of sleep duration and sleep disturbances on the incidence of dementia and Alzheimer's disease: A 10-year follow-up study2024Ingår i: Psychiatry Research, ISSN 0165-1781, E-ISSN 1872-7123, Vol. 333, artikel-id 115760Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nature of the relationship between sleep problems and dementia remains unclear. This study investigated the relationship between sleep measures and dementia in older adults (≥ 65) using data from the English Longitudinal Study of Ageing (ELSA) and further investigated the causal association in Mendelian randomization (MR) analysis. In total of 7,223 individuals, 5.7 % developed dementia (1.7 % Alzheimer's disease (AD)) within an average of 8 (± 2.9) years. Cox regression models and MR were employed. Long sleep duration (>8 h) was associated with 64 % increased risk of incident dementia and 2-fold high risk of AD compared to ideal sleep duration (7–8 h). This association was particularly evident in older-older adults (≥70 years) and those who consumed alcohol. Short sleep duration (<7 h) was associated with lower risk of incident dementia among older-older but higher risk among younger-older adults. Sleep disturbances and perceived sleep quality were not associated with dementia or AD. The MR study did not reveal causal associations between sleep duration and dementia. These findings suggest that self-reported short sleep in younger-older and long sleep in older-older adults and those with frequent alcohol consumption are associated with dementia. Early detection of these sleep patterns may help identify individuals at higher dementia risk.

  • 152. Åkerstedt Miley, Anna
    et al.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Comparing two versions of the Karolinska Sleepiness Scale (KSS)2016Ingår i: Sleep and Biological Rhythms, ISSN 1446-9235, E-ISSN 1479-8425, Vol. 14, nr 3, s. 257-260Artikel i tidskrift (Refereegranskat)
    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.

  • 153.
    Åkerstedt, Torbjorn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Narusyte, Jurgita
    Svedberg, Pia
    Night work, mortality, and the link to occupational group and sex2020Ingår i: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 46, nr 5, s. 508-515Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective Night shifts are associated with several major diseases. Mortality has been studied only to a limited extent, and the association with night shifts remains unclear. The purpose of the present study was to investigate the association between duration of night shift exposure and mortality in a large sample from the Swedish Twin Registry (the SALT cohort).

    Methods Cox proportional hazards regression models were used to analyze the data (N=42 731) over a followup period of 18 years, with years of night shift work as the exposure variable and adjustment for lifestyle factors and age, and stratification on gender and occupational group.

    Results The hazard ratio (HR) for “ever” night shifts for total mortality was 1.07 [95% confidence interval (CI) 1.01–1.15] but 1.15 (95% CI 1.07–1.25) for longer exposure (>5 years). Also, HR for cause-specific mortality due to cardiovascular disease was significant, with higher HR for longer night shift exposure. Mortality due to cancer was significant for longer exposure only. White-collar workers showed significant HR for longer exposure. In particular, male white-collar workers showed a significant HR, with a highest value for longer exposure [HR 1.28 (95% CI 1.09–1.49)]. Heredity did not influence the results significantly.

    Conclusions Long duration of exposure to night shift work is associated with increased mortality, particularly in male white-collar workers. The lack of effects of accumulated exposure suggests that the results should be interpreted with caution.

  • 154.
    Åkerstedt, Torbjorn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Schwarz, Johanna
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Gruber, Georg
    Theorell-Haglöw, Jenny
    Lindberg, Eva
    Short sleep-poor sleep? A polysomnographic study in a large population-based sample of women2019Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 28, nr 4, artikel-id e12812Artikel i tidskrift (Refereegranskat)
    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.

  • 155.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen.
    Altered sleep/wake patterns and circadian rhythms: laboratory and field studies of sympathoadrenomedullary and related variables1979Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Six studies on sleep/wake patterns and circadian rhythms were  carried out. In summary: (1) Adrenaline excretion, self-rated activation,  and body temperature rhythms persisted during sleep  deprivation, resisted adjustment to rotating shift work, but adjusted  rather well to permanent night work. Noradrenaline adjusted  to most schedules and lost its rhythm during sleep deprivation.  When night sleep was reintroduced the noradrenaline rhythm  reappeared while the existing adrenaline rhythm was accentuated.  (2) Exposure to a performance stressor at the trough raised adrenaline  to daytime levels. An equally large response was seen at the  peak. (3) Interindividual day-to-day consistency of 3 and 24 hour  levels was high for both catecholamines. Intraindividual consistency  of the 24-hour pattern was high for adrenaline but low for noradrenaline.  Cosine estimates of adrenaline phase showed a considerable  intraindividual consistency while interindividual consistency  was poor. Noradrenaline had poor cosine fit. (4) Sleep deprivation  did not change catecholamine excretion either during the  vigil or during recovery sleep. (5) It was concluded that adrenaline  excretion, rated alertness, and body temperature exhibited selfsustained  circadian rhythms which made adjustment to new sleep/  wake patterns very difficult, and that the noradrenahne excretion  rhythm depended on exogenous factors.  

  • 156.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Arbete som stör dygnsrytmen2008Ingår i: Arbetslivsfysiologi, Studentlitteratur, Lund , 2008, s. 279-306Kapitel i bok, del av antologi (Övrig (populärvetenskap, debatt, mm))
  • 157.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Occupational Impact2013Ingår i: Encyclopedia of Sleep / [ed] Clete Kushida, Academic Press, 2013, s. 308-310Kapitel i bok, del av antologi (Refereegranskat)
    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.

  • 158.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Shift Work - Sleepiness and Sleep in Transport2019Ingår i: Sleep Medicine Clinics, ISSN 1556-407X, E-ISSN 1556-4088, Vol. 14, nr 4, s. 413-421Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Driving a vehicle during a night shift increases the accident risk and incidents of falling asleep at the wheel. Individuals having worked a night shift (in any type of occupation) run a similar risk when commuting home from a night shift. Early starts of driving may increase risk. Detailed field studies of sleepiness indicate high levels of sleepiness during late night driving. The mechanism includes exposure to the circadian trough of alertness during work and sleep loss. High levels of sleepiness and sleep loss associated with night and early morning work define the diagnosis of shift work disorder.

  • 159.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Social and Economic Impact2013Ingår i: Encyclopedia of Sleep / [ed] Clete Kushida, Academic Press, 2013, s. 306-307Kapitel i bok, del av antologi (Refereegranskat)
    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.

  • 160.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Sömnen2012Ingår i: Hjärnan / [ed] Lars Olson och Anna Josephson, Solna: Karolinska Institutet University Press , 2012, 2, s. 145-161Kapitel i bok, del av antologi (Refereegranskat)
  • 161.
    Åkerstedt, Torbjörn
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Återhämtning och sömn2012Ingår i: Psykosocial miljö och stress / [ed] Töres Theorell, Lund: Studentlitteratur AB, 2012, 2, s. 81-90Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 162.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Alfredsson, L
    Westerholm, P
    Fischer, H
    Nilsson, L-G
    Nordin, M
    Fatigue/sleepiness and important aspects of sleep restoration improve across aging2014Konferensbidrag (Övrigt vetenskapligt)
  • 163.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet.
    Anund, Anna
    Axelsson, John
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Subjective sleepiness is a sensitive indicator of insufficient sleep and impaired waking function2014Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 23, nr 3, s. 240-252Artikel i tidskrift (Refereegranskat)
    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.

  • 164.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Axelsson, John
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Individual validation of model predictions of sleepiness and sleep hours2007Ingår i: Somnologie, Vol. 11, s. 169-174Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    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.

  • 165.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Axelsson, John
    Lekander, Mats
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Orsini, Nicola
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Do sleep, stress, and illness explain daily variations in fatigue?: A prospective study2014Ingår i: Journal of Psychosomatic Research, ISSN 0022-3999, E-ISSN 1879-1360, Vol. 76, nr 4, s. 280-285Artikel i tidskrift (Refereegranskat)
    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.

  • 166.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Axelsson, John
    Lekander, Mats
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Orsini, Nicola
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    The daily variation in sleepiness and its relation to the preceding sleep episode - a prospective study across 42days of normal living2013Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 22, nr 3, s. 258-265Artikel i tidskrift (Refereegranskat)
    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.

  • 167.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Biologisk psykologi. Karolinska Institutet, Sweden.
    Bellocco, Rino
    Widman, Linnea
    Eriksson, Julia
    Ye, Weimin
    Adami, Hans-Olov
    Trolle Lagerros, Ylva
    The association of short and long sleep with mortality in men and women2024Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 33, nr 2, artikel-id e13931Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Both short (< 6 hr) and long (> 8 hr) sleep are associated with increased mortality. We here investigated whether the association between sleep duration and all-cause, cardiovascular disease and cancer mortality differs between men and women. A cohort of 34,311 participants (mean age and standard deviation = 50.5 ± 15.5 years, 65% women), with detailed assessment of sleep at baseline and up to 20.5 years of follow-up (18 years for cause-specific mortality), was analysed using Cox proportional hazards model to estimate HRs with 95% confidence intervals. After adjustment for covariates, all-cause, cardiovascular disease and cancer mortalities were increased for both < 5 hr and ≥ 9 hr sleep durations (with 6 hr as reference). For all-cause mortality, women who slept < 5 hr had a hazard ratio = 1.54 (95% confidence interval = 1.32–1.80), while the corresponding hazard ratio was 1.05 (95% confidence interval = 0.88–1.27) for men, the interaction being significant (p < 0.05). For cardiovascular disease mortality, exclusion of the first 2 years of exposure, as well as competing risk analysis eliminated the originally significant interaction. Cancer mortality did not show any significant interaction. Survival analysis of the difference between the reference duration (6 hr) and the short duration (< 5 hr) during follow-up showed a gradually steeper reduction of survival time for women than for men for all-cause mortality. We also observed that the lowest cancer mortality appeared for the 5-hr sleep duration. In conclusion, the pattern of association between short sleep duration and all-cause mortality differed between women and men, and the difference between men and women increased with follow-up time.

  • 168.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden .
    Discacciati, Andrea
    Habel, Henrike
    Westerlund, Hugo
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Psychosocial work demands and physical workload decrease with ageing in blue-collar and white-collar workers: a prospective study based on the SLOSH cohort2019Ingår i: BMJ Open, E-ISSN 2044-6055, Vol. 9, nr 9, artikel-id e030918Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives Psychosocial work demands and physical workload are important causes of ill health. The dramatic demographic changes in society make it important to understand if such factors change with ageing, but this is presently not known. The purpose of the present study was to investigate whether psychosocial work demands and physical workload change across 8years of ageing, whether occupational groups show different trajectories of change and if such trajectories are reflected in sleep or fatigue. Methods A cohort of 5377 participants (mean age: 47.611.6 (SD) years, 43.2% males, 40.2% blue-collar workers) was measured through self-report in five biannual waves across 8 years. Mixed model regression analyses was used to investigate change across ageing. Results Psychosocial work demands decreased significantly across 8 years (Coeff: -0.016 +/- 0.001), with the strongest decrease in the high white-collar group (Coeff=-0.031 +/- 0.003) and the oldest group. Physical workload also decreased significantly (Coeff=-0.032 +/- 0.002), particularly in the blue-collar group (Coeff=-0.050 +/- 0.004) and in the oldest group. Fatigue decreased, and sleep problems increased with ageing, but with similar slopes in the occupational groups. All effect sizes were small, but extrapolation suggests substantial decreases across a working life career. Conclusions The decrease in psychosocial work demands and physical workload suggests that the burden of work becomes somewhat lighter over 8 years. The mechanism could be 'pure' ageing and/or increased experience or related factors. The gradual improvement in the work situation should be considered in the discussion of the place of older individuals in the labour market, and of a suitable age for retirement. The results also mean that prospective studies of work and health need to consider the improvement in working life with ageing.

  • 169.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Discacciati, Andrea
    Miley-Åkerstedt, Anna
    Westerlund, Hugo
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Aging and the Change in Fatigue and Sleep - A Longitudinal Study Across 8 Years in Three Age Groups2018Ingår i: Frontiers in Psychology, E-ISSN 1664-1078, Vol. 9, artikel-id 234Artikel i tidskrift (Refereegranskat)
    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.

  • 170.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Folkard, Simon
    Portin, Christian
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Predictions from the Three-Process Model of Alertness2004Ingår i: Aviation, Space, and Environmental Medicine, ISSN 0095-6562, Vol. 75, nr 3, Suppl., s. A75-A83Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper summarizes a computer model for predicting alertness/performance in daily life. The model uses the timing of work hours (and/or sleep hours) as input and uses both a circadian and a homeostatic component (amount of prior wake and amount of prior sleep) that are summed to yield predicted subjective alertness (on a scale between 1 and 21). The model also includes prediction of psychomotor performance on various tasks, an identification of levels at which the risk of performance/alertness impairment start, as well as a prediction of sleep latency and time of awakening from sleep. The model is currently being used to evaluate work/rest schedules for navy, airline and railway applications. It is also used for teaching sleep/wake regulation and for generating research hypotheses.

  • 171.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Garefelt, Johanna
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Richter, Anne
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen. Karolinska Institutet, Sweden.
    Westerlund, Hugo
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Magnusson Hanson, Linda L.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Sverke, Magnus
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen. North West University, South Africa.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Work and Sleep - A Prospective Study of Psychosocial Work Factors, Physical Work Factors, and Work Scheduling2015Ingår i: Sleep, ISSN 0161-8105, E-ISSN 1550-9109, Vol. 38, nr 7, s. 1129-1136Artikel i tidskrift (Refereegranskat)
    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.

  • 172.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Ghilotti, Francesca
    Grotta, Alessandra
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Centrum för forskning om ojämlikhet i hälsa (CHESS). Karolinska Institutet, Sweden.
    Bellavia, Andrea
    Trolle Lagerros, Ylva
    Bellocco, Rino
    Sleep duration, mortality and the influence of age2017Ingår i: European Journal of Epidemiology, ISSN 0393-2990, E-ISSN 1573-7284, Vol. 32, nr 10, s. 881-891Artikel i tidskrift (Refereegranskat)
    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.

  • 173.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Ghilotti, Francesca
    Grotta, Alessandra
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Centrum för forskning om ojämlikhet i hälsa (CHESS). Karolinska Institutet, Sweden.
    Zhao, Hongwei
    Adami, Hans-Olov
    Trolle-Lagerros, Ylva
    Bellocco, Rino
    Sleep duration and mortality - Does weekend sleep matter?2019Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 28, nr 1, artikel-id e12712Artikel i tidskrift (Refereegranskat)
    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.

  • 174.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Hallvig, David
    Anund, Anna
    Fors, Carina
    Schwarz, Johanna
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Having to stop driving at night because of dangerous sleepiness - awareness, physiology and behaviour2013Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 22, nr 4, s. 380-388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A large number of accidents are due to the driver falling asleep at the wheel, but details of this link have not been studied on a real road. The purpose of the present study was to describe the development of sleepiness indicators, leading to the drive being terminated prematurely by the onboard expert driving instructor because of imminent danger. Eighteen individuals participated during a day drive and a night drive on a motorway (both 90 min). Eight drivers terminated (N) prematurely (after 43 min) because of sleep-related imminent danger [according to the driving instructor or their own judgement (two cases)]. The results showed very high sleepiness ratings (8.5 units on the Karolinska Sleepiness Scale) immediately before termination (<7 at a similar time interval for those 10 who completed the drive). Group N also showed significantly higher levels of sleep intrusions on the electroencephalography/electro-oculography (EEG/EOG) than those who completed the drive (group C). The sleep intrusions were increased in group N during the first 40 min of the night drive. During the day drive, sleep intrusions were increased significantly in group N. The night drive showed significant increases of all sleepiness indicators compared to the day drive, but also reduced speed and driving to the left in the lane. It was concluded that 44% of drivers during late-night driving became dangerously sleepy, and that this group showed higher perceived sleepiness and more sleep intrusions in the EEG/EOG.

  • 175.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Hallvig, David
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. 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 workers2017Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 26, nr 5, s. 559-566Artikel i tidskrift (Refereegranskat)
    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.

  • 176.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Ingre, Michael
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    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 project2010Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 19, nr 2, s. 298-309Artikel i tidskrift (Refereegranskat)
    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.

  • 177.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Sleep, Work, and Occupational Stress2012Ingår i: The Oxford Handbook of Sleep and Sleep disorders / [ed] Charles M. Morin, Colin Espie, New York: Oxford University Press , 2012, s. 248-265Kapitel i bok, del av antologi (Refereegranskat)
  • 178.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Säkerhet, arbetstider och trötthet2013Ingår i: Patientsäkerhet: teori och praktik / [ed] Synnöve Ödegård, Stockholm: Liber, 2013Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 179.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    What work schedule characteristics constitute a problem to the individual? A representative study of Swedish shift workers2017Ingår i: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 59, s. 320-325Artikel i tidskrift (Refereegranskat)
    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.

  • 180.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Axelsson, John
    Impaired sleep after bedtime stress and worries.2007Ingår i: Biol Psychol, ISSN 0301-0511, Vol. 76, nr 3, s. 170-3Artikel i tidskrift (Övrigt vetenskapligt)
    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]

  • 181.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Axelsson, John
    Subjective and objective quality of sleep: [Subjektive und objektive Schlafqualität]2008Ingår i: Somnologie, ISSN 1432-9123, E-ISSN 1439-054X, Vol. 12, s. 104-109Artikel i tidskrift (Övrigt vetenskapligt)
    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.

  • 182.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Selén, Jan
    Disturbed sleep and fatigue as predictors of return from long-term sickness absence2010Ingår i: Industrial Health, ISSN 0019-8366, E-ISSN 1880-8026, Vol. 48, nr 2, s. 209-14Artikel i tidskrift (Refereegranskat)
    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.

  • 183.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Klemets, Tomas
    Karlsson, David
    Häbel, Henrike
    Widman, Linnea
    Sallinen, Mikael
    Acute and cumulative effects of scheduling on aircrew fatigue in ultra-short-haul operations2021Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 30, nr 5, artikel-id e13305Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aircrew fatigue constitutes a safety hazard in aviation, which authorities attempt to mitigate through flight time limitations. Some gaps in knowledge exist, however. The purpose of the present study was to investigate the associations of schedule characteristics with fatigue and amount of sleep in the acute 24-h window, and as cumulative effects across the 7-day work period. One hundred and six aircrew (14% cabin crew) participated. They rated fatigue on the Karolinska Sleepiness Scale (KSS) three times per flight day for four 7-day work periods, with up to 7 days off between work periods. Mixed model regression was applied to the data. In the multivariable model, more sleep was associated with lower fatigue (p = .000)), corresponding to 0.26 KSS units less per hour of sleep. Very early, early and late duty types, as well as duty time, were associated with higher fatigue. For the 7-day work period, accumulation of very early duties and longer duty time were associated with increased fatigue, and more accumulated sleep was associated with lower fatigue in the adjusted model (0.08 KSS units per hour of sleep) (p = .000). Accumulated duty time was not significant when analysed as a single variable, but became so after adjustment for sleep. The results suggest that sleep, duty time and early starts are important predictors of fatigue in the 24-h window and that the number of very early starts and short sleep have cumulative effects on fatigue across a 7-day work period.

  • 184.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Knutsson, Anders
    Narusyte, Jurgita
    Svedberg, Pia
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Radboud University Nijmegen, Netherlands.
    Alexanderson, Kristina
    Night work and breast cancer in women: a Swedish cohort study2015Ingår i: BMJ Open, E-ISSN 2044-6055, Vol. 5, nr 4, artikel-id e008127Artikel i tidskrift (Refereegranskat)
    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.

  • 185.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Lekander, Mats
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Nilsonne, Gustav
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Fischer, Håkan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Biologisk psykologi.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    d'Onofrio, Paolo
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Gruber, G.
    Schwarz, Johanna
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Women sleep better and have a stronger response to late night curtailed sleep than men, particularly in older individuals - effects on polysomnographical sleep2016Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 25, s. 156-156, artikel-id P206Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives: Higher age is associated with poorer sleep and women report more sleep problems than men, despite indications of better physiological sleep. The purpose of the present study was to investigate whether a common daily life sleep problem, late night curtailed sleep, would have different effects depending on gender and age. Methods: 60 healthy individuals (equal groups of gender and age (20–30 and 65–75 years)) participated in an experiment with a full night’s sleep and one night with reduced sleep between 0400 h and 0700 h, in a balanced design. Sleep was recorded through standard polysomnography (PSG) at home. Results: The results showed the expected main effect of sleep loss. Older participants had a lower TST, N3%, sleep efficiency, but more N1%, longer N3 latency, and fewer awakenings. Women had more N3%, more REM%, more N3%, and shorter N3 latency compared with men. The curtailed late night sleep caused a stronger increase in N3%, and more pronounced reductions in REM%, a stronger reduction in N1%, and N3 latency in women than men. In the higher age group the N3% response in men was strongly attenuated compared to that of women. Conclusions: The results show that women, apart form getting more N3% and less N1% even in the normal sleep condition, have a stronger response to late night sleep, particularly in higher age groups.

  • 186.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Lekander, Mats
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Nilsonne, Gustav
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Tamm, S.
    d'Onofrio, Paolo
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Fischer, Håkan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Biologisk psykologi.
    Petrovic, P.
    Månsson, Kristoffer N.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Klinisk psykologi. Karolinska Institutet, Sweden.
    Gray Matter Volume Correlates Of Sleepiness: A Voxel-based Morphometry Study In Younger And Older Adults2018Ingår i: Sleep, ISSN 0161-8105, E-ISSN 1550-9109, Vol. 41, s. A58-A58, artikel-id 0149Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Introduction: Sleepiness is prevalent in society, often linked to disturbed sleep, shift work, stress, or diseases. It is also associated with an increased risk of accidents. Sleepiness may be related to brain metabolism and, we hypothesize that it is associated with brain gray matter (GM) volume. The present study investigated the association between sleepiness and GM volume in thalamus and insula, with a special focus on age, since both sleepiness and GM volume change with age.

    Methods: In all, 84 healthy individuals participated in the experiment, of which 46 were in the age range 20–30 years and 38 ranging between 65–75 years. Data was collected in a 3 T scanner during a 5 minute anatomical scan (first in a several sessions in the scanner) in the evening after a full night of sleep. Momentary sleepiness (Karolinska Sleepiness Scale) was rated 7 times during the time in the scanner.

    Results: Results showed that, in older, relative to younger adults, areas within bilateral insular cortex and thalamus GM regions of interest were negatively associated (FWE-corrected) with sleepiness (Z=4.02, p=.015 left insula and Z=4.42, p=.009 for right insula; Z=3.75, p=.020 for left thalamus and Z=4.60, p=.001 for right thalamus). Larger volume was associated with low sleepiness in the older group, but not in the older group. The effect in the insula was mainly present in the mid-anterior parts of the structure.. In addition, after applying a conservative small volume correction including all ROIs simultaneously, age-interaction effects remained significant.

    Conclusion: It was concluded that self-rated momentary sleepiness in a monotonous situation is negatively associated with GM volume in areas within both thalamus and insula in older individuals. The results are in line with notions of thalamus as a driver of arousal and of anterior insula as a structure evaluating the state of the organism. Possibly, a larger GM volume in these structures may be protective against sleepiness in older individuals, a hypothesis that needs confirmation in further studies.

  • 187.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Lekander, Mats
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Nilsonne, Gustav
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Tamm, Sandra
    D'onofrio, Paolo
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Fischer, Håkan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Biologisk psykologi.
    Schwarz, Johanna
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Effects of late-night short-sleep on in-home polysomnography: relation to adult age and sex2018Ingår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27, nr 4, artikel-id e12626Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bedtime is frequently delayed by many factors in life, and a homeostatic response to the delay may compensate partly for increased time awake and shortened sleep. Because sleep becomes shorter with age and women complain of disturbed sleep more often than men, age and sex differences in the homeostatic response to a delayed bedtime may modify the homeostatic response. The purpose of the present study was to investigate the effect of late-night short-sleep (3 h with awakening at about 07:00 hours) on in-home recorded sleep in men and women in two age groups (20-30 and 65-75 years). Results (N = 59) showed that late-night short-sleep was associated with an increase in percentage of N3 sleep and a decrease in percentage of rapid eye movement sleep, as well as decreases in several measures of sleep discontinuity and rapid eye movement density. Men showed a smaller decrease in percentage of rapid eye movement sleep than women in response to late-night short-sleep, as did older individuals of both sexes compared with younger. Older men showed a weaker percentage of N3 sleep in response to late-night short-sleep than younger men. In general, men showed a greater percentage of rapid eye movement sleep and a lower percentage of N3 sleep than women, and older individuals showed a lower percentage of N3 sleep than younger. In particular, older men showed very low levels of percentage of N3 sleep. We conclude that older males show less of a homeostatic response to late-night short-sleep. This may be an indication of impaired capacity for recovery in older men. Future studies should investigate if this pattern can be linked to gender-associated differences in morbidity and mortality.

  • 188.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Lekander, Mats
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Nilsonne, Gustav
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Tamm, Sandra
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    d'Onofrio, Paolo
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Fischer, Håkan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Biologisk psykologi.
    Schwarz, Johanna
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Petrovic, Predrag
    Månsson, Kristoffer NT
    Gray Matter Volume Correlates of Sleepiness: A Voxel-Based Morphometry Study in Younger and Older Adults2020Ingår i: Nature and Science of Sleep, ISSN 1179-1608, Vol. 12, s. 289-298Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Subjectively experienced sleepiness is a problem in society, possibly linked with gray matter (GM) volume. Given a different sleep pattern, aging may affect such associations, possibly due to shrinking brain volume.

    Purpose: The purpose of the present study was to investigate the association between subjectively rated sleepiness and GM volume in thalamus, insula, hippocampus, and orbitofrontal cortex of young and older adults, after a normal night’s sleep.

    Methods: Eighty-four healthy individuals participated (46 aged 20– 30 years, and 38 aged 65– 75 years). Morphological brain data were collected in a 3T magnetic resonance imaging (MRI) scanner. Sleepiness was rated multiple times during the imaging sessions.

    Results: In older, relative to younger, adults, clusters within bilateral mid-anterior insular cortex and right thalamus were negatively associated with sleepiness. Adjustment for the immediately preceding total sleep time eliminated the significant associations.

    Conclusion: Self-rated momentary sleepiness in a monotonous situation appears to be negatively associated with GM volume in clusters within both thalamus and insula in older individuals, and total sleep time seems to play a role in this association. Possibly, this suggests that larger GM volume in these clusters may be protective against sleepiness in older individuals. This notion needs confirmation in further studies.

  • 189.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Lekander, Mats
    Petersén, Helena
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Axelsson, John
    Sleep Polysomnography and Reported Stress across 6 Weeks2014Ingår i: Industrial Health, ISSN 0019-8366, E-ISSN 1880-8026, Vol. 52, nr 1, s. 36-42Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the common notion that stress impairs sleep there is little published data showing that sleep (polysomnography [PSG]) is impaired across several sleep episodes in individuals who complain of daily stress during the same period. The present paper aimed at investigating such a connection. 33 subjects had 3 sleeps recorded with PSG at home across 6 weeks and kept a sleep/wake diary each day, including 3-hourly ratings of stress (scale 1-9). The stress ratings and the conventional PSG parameters were averaged across time. A stepwise multiple regression analysis showed that the best predictors of stress were Stage 1 sleep (beta=0.49), latency to Stage 1 sleep (0.47) (adjusted for anxiety and age). Other sleep continuity variables had significant correlations with stress (reversed) but did not enter the multiple regression analysis. The correlation between stress before the start of the study and PSG data was not significant. It was concluded that moderately increased stress over a longer period of time is related to moderate signs of disturbed sleep during that period. This may be of importance when considering stress as a work environment problem.

  • 190.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Lindberg, E
    Gruber, G
    Theorell-Haglöw, J
    Schwarz, Johanna F A
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    What does good sleep in terms of macro and microstructure of sleep in women and how does age affect this relation?2014Ingår i: Journal of sleep research, Special issue: 22nd Congress of the European Sleep Research Society, 16-20 September 2014, Tallinn, Estonia, 2014Konferensbidrag (Övrigt vetenskapligt)
  • 191.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet.
    Lindbäck, G.
    Karolinska institutet, Stockholm.
    Night Shiftwork2007Ingår i: The Encyclopedia of Stress, Academic Press, 2007, 2, s. 917-920Kapitel i bok, del av antologi (Refereegranskat)
  • 192.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Narusyte, Jurgita
    Alexanderson, Kristina
    Svedberg, Pia
    Sleep Duration, Mortality, and Heredity-A Prospective Twin Study2017Ingår i: Sleep, ISSN 0161-8105, E-ISSN 1550-9109, Vol. 40, nr 10, artikel-id zsx135Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Introduction

    A number of studies have shown a U-shaped association between sleep duration and mortality. Since sleep duration is partly genetically determined, it seems likely that its association with mortality is also genetically influenced. The purpose of the present study was to investigate the influence on heredity on the association between sleep duration and mortality.

    Methods

    We used a cohort of 14 267 twins from the Swedish Twin Registry.

    Results

    A Cox proportional hazards regression analysis, adjusted for a number of covariates, confirmed a clear U shape with a hazard ratio (HR) = 1.34 and 95% confidence interval (CI) = 1.15-1.57 for a sleep duration of = 6.5 hours and HR = 1.18 (CI = 1.07-1.30) for sleep of = 9.5 hours. Reference value was 7.0 hours. A co-twin analysis of 1942 twins discordant on mortality showed a HR = 2.66 (CI = 1.17-6.04) for long (= 9.5 hours) sleep in monzygotic twins and an HR = 0.66 (CI = 0.20-2.14) for short (< 6.5 hours) sleep. In dizygotic twins, no association was significant. The heritability for mortality was 28% for the whole group, while it was 86% for short sleepers and 42% for long sleepers. Thus, the link with mortality for long sleep appears to be more due to environmental factors than to heredity, while heritability dominates among short sleepers.

    Conclusions

    We found that both long and short sleep were associated with higher total mortality, that the difference in mortality within twin pairs is associated with long sleep, and that short sleep has a higher heritability for mortality, while long sleep is associated with more environmental influences on mortality.

  • 193.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Narusyte, Jurgita
    Svedberg, Pia
    Sleep duration and mortality - Influence of age and occupational group in retired individuals2021Ingår i: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 80, s. 199-203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The importance of sleep duration for health or mortality attracts much public attention. Prior work indicates that both long and short sleep duration predicts mortality, with optimal sleep duration (lowest risk) at 7 h. However, we believe this may differ between subgroups. This may be the case with, for example, age groups (due to aging), or blue-collar and white-collar worker (due to work exposure). It is also likely that retirement, which permits extension of the time in bed, may confound analyses. The purpose of the present study was to investigate how occupational group (blue-collar/white-collar worker) and age influence the pattern of association between sleep duration and mortality in retired individuals. Retired individuals were selected since it was hypothesized that effects of occupation may accumulate over years and since the transition into retirement may be a confounder. We used a sample of 14 000 individuals from the Swedish Twin Registry, which had provided data on sleep duration and a number of covariates. Cox proportional hazards analysis was applied to data. The results show that occupational group did not influence the association, but showed significant hazard ratios (HR) for long (>= 9.5 h) and short (<6.5 h) sleep in both groups (HR > 1.35), with optimal sleep duration (lowest HR) with a wide span (6.5-9.5 h). Age groups in tertiles also showed significant U-shapes, with a wide span (6.5-9.5 h) for the younger 2/3 (54-74 years), but a weaker pattern for the oldest third (>= 75 years), for which optimal sleep fell in the 6.5-7.5 h interval. It was concluded that occupational group does not influence the association between sleep duration and mortality in retired individuals, but that age does.

  • 194.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Narusyte, Jurgita
    Svedberg, Pia
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Radboud University, The Netherlands .
    Alexanderson, Kristina
    Night work and prostate cancer in men: a Swedish prospective cohort study2017Ingår i: BMJ Open, E-ISSN 2044-6055, Vol. 7, nr 6, artikel-id e015751Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives Prostate cancer is the most common cancer and the second leading cause of cancer-related deaths among men, but the contributing factors are unclear. One such may be night work because of the day/night alternation of work and the resulting disturbance of the circadian system. The purpose of the present study was to investigate the prospective relation between number of years with night work and prostate cancer in men.

    Design Cohort study comparing night and day working twins with respect to incident prostate cancer in 12 322 men.

    Setting Individuals in the Swedish Twin Registry.

    Participants 12 322 male twins.

    Outcome measures Prostate cancer diagnoses obtained from the Swedish Cancer Registry with a follow-up time of 12 years, with a total number of cases=454.

    Results Multiple Cox proportional hazard regression analysis, adjusted for a number of covariates, showed no association between ever night work and prostate cancer, nor for duration of night work and prostate cancer. Analysis of twin pairs discordant for prostate cancer (n=332) showed no significant association between night work and prostate cancer.

    Conclusions The results, together with previous studies, suggest that night work does not seem to constitute a risk factor for prostate cancer.

  • 195.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Psykologiska institutionen, Stressforskningsinstitutet. Karolinska Institute, Sweden.
    Nilsson, Peter M.
    Good night and sleep well! – But what is really a healthy sleep?2022Ingår i: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 291, nr 1, s. 5-7Artikel i tidskrift (Övrigt vetenskapligt)
  • 196.
    Åkerstedt, Torbjörn
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Nordin, Maria
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Umeå University, Sweden.
    Alfredsson, Lars
    Westerholm, Peter
    Kecklund, Göran
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Stressforskningsinstitutet. Karolinska Institutet, Sweden.
    Predicting changes in sleep complaints from baseline values and changes in work demands, work control, and work preoccupation - The WOLF-project2012Ingår i: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 13, nr 1, s. 73-80Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Study objective: Stress as a cause of disturbed sleep is often taken for granted, but the longitudinal evidence is limited. The aim of this study was to evaluate new cases of poor sleep as a function of changes in reported work demands, work control, and work preoccupation. Methods: Longitudinal study of change with measures occurring twice within a 5-year interval during a period when the prevalence of impaired sleep was increasing in Sweden. The sample of companies was taken from northern Sweden (Norrland) and included 3637 individuals from the "WOLF Norrland" longitudinal cohort, collected through company health services. Measurement and results: During the measurement period, 16% of those studied developed new cases of impaired sleep. Logistic regressions adjusted for demographics, work environment factors, and disturbed sleep at T1 period one showed a significant increase in new cases for high work demands and high work preoccupation (OR = 1.37; Ci = 1.09-1.72 and OR = 1.80; CI = 1.42-2.28, respectively). The analysis of change in the predictors showed effects of a change from low to high work demands (OR = 1.39; Ci = 1.00-1.95) on new cases of impaired sleep. Consistent high work demands (high at both points) showed a similar increase (OR = 1.49; Ci = 1.06-2.11) but no effect was seen for reduced demands. Change in work preoccupation yielded stronger effects with OR = 2.47 (1.78-2.47) for increased work preoccupation and OR = 3.79 (2.70-5.31) for consistent high work preoccupation. Also, a reduction in work preoccupation was associated with a reduction in new cases of disturbed sleep. Control at work was not related to sleep. Stratification with respect to gender mainly led to fewer significant results (particularly for women) due to larger confidence intervals. Conclusions: It was concluded that self-reported work preoccupation predicts subsequent impairment of sleep and that increased preoccupation is associated with new cases of impaired sleep. Similar, but weaker, results were obtained for work demands.

  • 197.
    Åkerstedt, Torbjörn