| 1. |
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| 2. |
- Akerstedt, Torbjörn, et al.
(author)
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Accounting for partial sleep deprivation and cumulative sleepiness in the Three-Process Model of alertness regulation.
- 2008
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In: Chronobiol Int. - : Informa UK Limited. - 1525-6073 .- 0742-0528. ; 25:2, s. 309-19
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Journal article (peer-reviewed)abstract
- Accounting for partial sleep deprivation and cumulative sleepiness in the Three-Process Model of alertness regulation.Akerstedt T, Ingre M, Kecklund G, Folkard S, Axelsson J.Stress Research Institute, University of Stockholm, Stockholm, Sweden. torbjorn.akerstedt@ki.seMathematical models designed to predict alertness or performance have been developed primarily as tools for evaluating work and/or sleep-wake schedules that deviate from the traditional daytime orientation. In general, these models cope well with the acute changes resulting from an abnormal sleep but have difficulties handling sleep restriction across longer periods. The reason is that the function representing recovery is too steep--usually exponentially so--and with increasing sleep loss, the steepness increases, resulting in too rapid recovery. The present study focused on refining the Three-Process Model of alertness regulation. We used an experiment with 4 h of sleep/night (nine participants) that included subjective self-ratings of sleepiness every hour. To evaluate the model at the individual subject level, a set of mixed-effect regression analyses were performed using subjective sleepiness as the dependent variable. These mixed models estimate a fixed effect (group mean) and a random effect that accounts for heterogeneity between participants in the overall level of sleepiness (i.e., a random intercept). Using this technique, a point was sought on the exponential recovery function that would explain maximum variance in subjective sleepiness by switching to a linear function. The resulting point explaining the highest amount of variance was 12.2 on the 1-21 unit scale. It was concluded that the accumulation of sleep loss effects on subjective sleepiness may be accounted for by making the recovery function linear below a certain point on the otherwise exponential function.
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| 3. |
- Akerstedt, Torbjörn, et al.
(author)
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Disturbed sleep in shift workers, day workers, and insomniacs.
- 2008
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In: Chronobiol Int. - : Informa UK Limited. - 1525-6073 .- 0742-0528. ; 25:2, s. 333-48
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Journal article (peer-reviewed)abstract
- Disturbed sleep in shift workers, day workers, and insomniacs.Akerstedt T, Ingre M, Broman JE, Kecklund G.Stress Research Institute, University of Stockholm, Karolinska Institutet, Stockholm, Sweden. torbjorn.akerstedt@ki.seVery little is known about differences in sleep between day and shift workers in representative samples of the population. This study compared a national representative sample (N=3400) of shift (with night shifts) and day workers regarding the different types of sleep disturbances and also the level of sleep symptoms with that of insomnia patients. The results showed very few differences between shift and day workers; only "too little sleep" and "nodding off at work" were marginally higher among shift workers. The results also showed that the complaints of insomnia patients for most sleep disturbances corresponded to the 2nd-16th percentile of the shift workers' levels of complaints. The results suggest, at least with the present questionnaire methodology, that shift work does not appear to be a major source of sleep disturbances and that their complaint levels bear no resemblance to those seen in insomniac patients.
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| 4. |
- Akerstedt, Torbjörn, et al.
(author)
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Effects of context on sleepiness self-ratings during repeated partial sleep deprivation.
- 2008
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In: Chronobiol Int. - : Informa UK Limited. - 1525-6073 .- 0742-0528. ; 25:2, s. 271-8
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Journal article (peer-reviewed)abstract
- Effects of context on sleepiness self-ratings during repeated partial sleep deprivation.Akerstedt T, Kecklund G, Axelsson J.Stress Research Institute, Stockholm University, Stockholm, Sweden. torbjorn.akerstedt@ki.seRatings of subjective sleepiness are often used in laboratory and field studies of sleep loss and shifted sleep hours. Some studies suggest that such ratings might fail to reflect sleepiness as shown in physiology or performance. One reason for this may be the influence of the context of the rating. Social interaction or physical activity may mask latent sleepiness. The present study attempted to approach this question. Nine subjects participated in a partial sleep-deprivation experiment (five days of 4 h of time in bed [TIB]), preceded by two baseline days (8 h TIB) and followed by three recovery days (8 h TIB). Sleepiness was self-rated on the Karolinska Sleepiness Scale (KSS; scores of 1-9) after a period of relaxation, after a reaction-time test, and after 30 min of free activities. The results showed a strong increase in subjective sleepiness during sleep restriction and a significant difference between conditions. Free activity reduced the self-rated subjective sleepiness by 1.1 KSS units compared to the level of sleepiness self-rated at the end of the reaction-time test. Thus, the results of this study indicate that the context of a sleepiness rating affects the outcome of the rating.
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| 5. |
- Akerstedt, Torbjörn, et al.
(author)
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Predicting road crashes from a mathematical model of alertness regulation--The Sleep/Wake Predictor.
- 2008
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In: Accid Anal Prev. - : Elsevier BV. - 0001-4575. ; 40:4, s. 1480-5
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Journal article (other academic/artistic)abstract
- Predicting road crashes from a mathematical model of alertness regulation--The Sleep/Wake Predictor.Akerstedt T, Connor J, Gray A, Kecklund G.Stress Research Institute, Stockholm University and Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. torbjorn.akerstedt@ki.seSleepiness is related to factors such as the time of day, the time since awakening and the duration of prior sleep. The present study investigated whether actual road crashes could be predicted from a mathematical model based on these three factors (the Sleep/Wake Predictor-SWP). Data were derived from a population-based case-control study of serious injury crashes. Data on accident time (or control sampling time) and start and end of prior sleep were entered into the model (blind). The predicted sleepiness values were used in logistic regressions. The results showed a highly significant odds ratio (OR)=1.72 (confidence interval=1.41-2.09) for each incremental step of sleepiness on the output sleepiness scale (nine steps). There was also a significant interaction with blood alcohol level, showing high OR values for high sleepiness levels and alcohol levels above 50 mg% (0.05 g/dl). It was concluded that the model is a good predictor of road crashes beyond that of alcohol level, and that interaction between the two carries a very high risk.
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| 6. |
- Akerstedt, Torbjörn, et al.
(author)
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Sleep and sleepiness in relation to stress and displaced work hours.
- 2007
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In: Physiol Behav. - : Elsevier BV. - 0031-9384. ; 92:1-2, s. 250-5
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Journal article (other academic/artistic)abstract
- Sleep and sleepiness in relation to stress and displaced work hours.Akerstedt T, Kecklund G, Gillberg M.Karolinska Institutet, Institute for Psychosocial Medicine Box 230, S-171 77 Stockholm, Sweden. torbjorn.akerstedt@ipm.ki.seSleep is an important factor in relation to accidents, long-term health and mortality. Our group has had a long-term commitment to research on sleep regulation and its consequences. Over the years we have demonstrated pronounced effects of night work on sleep and alertness, including electroencephalographically determined sleep during work. We have also demonstrated that experimental displacement of sleep will result in short sleep at daytime and increased physiological sleepiness at night and developed mathematical models for prediction of sleep duration, as well as of sleepiness and risk of sleep-related accidents. We have also looked at the concept of sleep quality and found it dependent on sleep duration, sleep continuity and content of sleep stages 3 and 4. Sleep is also clearly disturbed in patients on long-term sick leave for burnout or in non-patients with high burnout scores, in particular sleep fragmentation is increased and sleep efficiency and sleep stages 3 and 4 (SWS--deep sleep) decreased. The fragmentation in turn seems related to endocrine changes. Present work is focused on bringing this work together, connecting the links from stress to sleep to metabolic changes to disease and long-term sickness absence.PMID: 17585960 [PubMed - indexed for MEDLINE]
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| 7. |
- Akerstedt, Torbjörn, et al.
(author)
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Sleep homeostasis during repeated sleep restriction and recovery : support from EEG dynamics.
- 2009
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In: Sleep. - : Oxford University Press (OUP). - 0161-8105 .- 1550-9109. ; 32:2, s. 217-22
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Journal article (peer-reviewed)abstract
- STUDY OBJECTIVES: Sleep reduction normally causes a homeostatic response during subsequent recovery sleep, but this does not seem to be true for repeated partial sleep loss. The aim of the present study was to test the response to repeated partial sleep loss through detailed focus on spectral data and parts of sleep. DESIGN: The experiment involved 4 h of sleep across 5 days in the laboratory (partial sleep deprivation [PSD]), followed by 3 days of recovery sleep. PSD was achieved through a delayed bedtime. Nine individuals participated. To avoid "laboratory monotony," subjects were permitted to leave the lab for a few hours each day. MEASUREMENTS AND RESULTS: All sleep stages and the latencies to sleep and slow wave sleep (SWS) showed a significant reduction during PSD. However, SWS and TST (total sleep time) during the first half of sleep increased gradually across days with PSD. During the first recovery sleep, SWS was significantly increased, while stage 1 and latency to stage 3 were reduced. All were back to baseline on the second night of recovery sleep. Summed spectral power during the first 3.8 h of sleep showed a gradual and robust increase (50% above baseline) in the range 1.25-7.25 Hz across days with PSD up to first recovery sleep and then returned to baseline. CONCLUSIONS: SWS and summed power density in a broad low-frequency band respond to repeated partial sleep deprivation in a dose-response fashion during the first 4 h sleep, apparently reflecting a robust and stable homeostatic response to sleep loss.
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| 8. |
- Anund, Anna, et al.
(author)
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Driver sleepiness and individual differences in preferences for countermeasures.
- 2008
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In: J Sleep Res. - : Wiley. - 1365-2869 .- 0962-1105. ; 17:1, s. 16-22
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Journal article (other academic/artistic)abstract
- 1: J Sleep Res. 2008 Mar;17(1):16-22. LinksDriver sleepiness and individual differences in preferences for countermeasures.Anund A, Kecklund G, Peters B, Akerstedt T.Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden. anna.anund@vti.seThe aim of the present national questionnaire study was to relate the use of sleepiness countermeasures among drivers to possible explanatory factors such as age, sex, education, professional driving, being a shift worker, having experience of sleepy driving, sleep-related crashes, problems with sleep and sleepiness in general and sleep length during working days. Also the attitude to countermeasures related to information or driver support system was studied. A random sample of 3041 persons was drawn from the national register of vehicle owners. The response rate was 62%. The most common countermeasures were to stop to take a walk (54%), turn on the radio/stereo (52%), open a window (47%), drink coffee (45%) and to ask passengers to engage in conversation (35%). Logistic regression analysis showed that counteracting sleepiness with a nap (a presumably efficient method) was practiced by those with experience of sleep-related crashes or of driving during severe sleepiness, as well as by professional drivers, males and drivers aged 46-64 years. The most endorsed means of information to the driver about sleepiness was in-car monitoring of driving performance providing drivers with information on bad or unsafe driving. This preference was related to experience of sleepy driving, not being a professional driver and male gender. Four clusters of behaviours were identified: alertness-enhancing activity while driving (A), stopping the car (S), taking a nap (N) and ingesting coffee or other sources of caffeine (C) (energy drinks, caffeine tablets). The participants were grouped according to their use of any of the four categories of countermeasures. The most common cluster was those who used activity, as well as stopping and drinking caffeine.PMID: 18275551 [PubMed - in process]
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| 9. |
- Anund, Anna, et al.
(author)
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The alerting effect of hitting a rumble strip--a simulator study with sleepy drivers.
- 2008
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In: Accid Anal Prev. - : Elsevier BV. - 1879-2057 .- 0001-4575. ; 40:6, s. 1970-6
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Journal article (peer-reviewed)abstract
- The alerting effect of hitting a rumble strip--a simulator study with sleepy drivers.Anund A, Kecklund G, Vadeby A, Hjälmdahl M, Akerstedt T.Clinical Neuroscience, Karolinska Institutet, SE-177 71 Stockholm, Sweden. anna.anund@vti.seA moving base driving simulator experiment was carried out in order to investigate the effects of milled rumble strips on driver fatigue. There were rumble strips both at the edge line and centre line. Four different physical designs of milled rumble strips (yielding noise values from 1.5 to 16 dBA) and two placements on shoulder were used in the experiment. Sound and vibrations from real milled rumble strips were reproduced in the simulator. In total 35 regular shift workers drove during the morning hours after a full night shift. The main results showed an increase in sleepiness indicators (EEG alpha/theta activity, eye closure duration, standard deviation of lateral position, subjective sleepiness) from start to before hitting the rumble strip, an alerting effect in most parameters (not subjective sleepiness) after hitting the strip. The alertness enhancing effect was, however, short and the sleepiness signs returned 5 min after the rumble strip hit. Essentially no effects were seen due to type of strip. It was concluded that various aspects of sleepiness are increased before hitting a rumble strip and that the effect is very short-lived. Type of strip, as used in the present study did not have any effect.
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| 10. |
- Asberg, Marie, et al.
(author)
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Novel biochemical markers of psychosocial stress in women.
- 2009
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In: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 4:1
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Journal article (peer-reviewed)abstract
- BACKGROUND: Prolonged psychosocial stress is a condition assessed through self-reports. Here we aimed to identify biochemical markers for screening and early intervention in women. METHODS: Plasma concentrations of interleukin (IL) 1-alpha, IL1-beta, IL-2, IL-4, IL-6, IL-8, IL-10, interferon-gamma (INF-gamma), tumor necrosis factor-alpha (TNF-alpha), monocyte chemotactic protein-1 (MCP-1), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), thyroid stimulating hormone (TSH), total tri-iodothyronine (TT3), total thyroxine (TT4), prolactin, and testosterone were measured in: 195 women on long-term sick-leave for a stress-related affective disorder, 45 women at risk for professional burnout, and 84 healthy women. RESULTS: We found significantly increased levels of MCP-1, VEGF and EGF in women exposed to prolonged psychosocial stress. Statistical analysis indicates that they independently associate with a significant risk for being classified as ill. CONCLUSIONS: MCP-1, EGF, and VEGF are potential markers for screening and early intervention in women under prolonged psychosocial stress.
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| 11. |
- Axelsson, John, et al.
(author)
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Sleepiness and performance in response to repeated sleep restriction and subsequent recovery during semi-laboratory conditions.
- 2008
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In: Chronobiol Int. - : Informa UK Limited. - 1525-6073 .- 0742-0528. ; 25:2, s. 297-308
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Journal article (peer-reviewed)abstract
- Sleepiness and performance in response to repeated sleep restriction and subsequent recovery during semi-laboratory conditions.Axelsson J, Kecklund G, Akerstedt T, Donofrio P, Lekander M, Ingre M.Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. john.axelsson@ki.seThere is an ongoing debate of how best to measure the effects of sleep loss in a reliable and feasible way, partly because well controlled laboratory studies and field studies have come to different conclusions. The aims of the present study were to investigate both sleepiness and performance in response to long-term sleep restriction and recovery in a semi-laboratory environment, investigate order effects (i.e., whether levels return to baseline) in a study with seven days of recovery, and characterize individual differences in tolerance to restricted sleep. Nine healthy men (age 23-28 yrs) participated in the protocol, which included one habituation day (sleep 23:00-07:00 h), two baseline days (23:00-07:00 h), five days with restricted sleep (03:00-07:00 h), and seven recovery days (23:00-07:00 h). Participants went outdoors at least twice each day. Reaction-time tests were performed at 08:00, 14:00, and 20:00 h each day in the laboratory. Sleepiness was self-rated by the Karolinska Sleepiness Scale (KSS)after each test. The mixed-effect regression models showed that each day of restricted sleep resulted in an increase of sleepiness by 0.64+/- .05 KSS units (a nine-step scale, p < .001), increase of median reaction times of 6.6+/- 1.6 ms ( p = .003), and increase of lapses/test of 0.69 +/- .16 ms ( p < .001). Seven days of recovery allowed participants to return to the baseline for sleepiness and median reaction time, but not for lapses.The individual differences were larger for performance measures than for sleepiness; the between-subject standard deviation for the random intercept was in the magnitude of the effects of 1.1 days of restricted sleep for sleepiness, 6.6 days of restricted sleep for median reaction time, and 3.2 days for lapses. In conclusion, the present study shows that sleepiness is closely related to sleep pressure, while performance measures, to a larger extent, appear determined by specific individual traits. Moreover, it is suggested to measure sleepiness in a standardized situation so as to minimize the influences of contextual factors.
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| 12. |
- Dahlgren, Anna, et al.
(author)
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Day-to-day variation in saliva cortisol-Relation with sleep, stress and self-rated health.
- 2009
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In: Biological psychology. - : Elsevier BV. - 1873-6246 .- 0301-0511.
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Journal article (peer-reviewed)abstract
- The objective was to examine the day-to-day variation in cortisol among healthy individuals and its relation to the time of saliva sampling, work, stress and fatigue. During 4 consecutive weeks, 14 office workers provided saliva samples (at awakening, 15min after awakening and at bedtime) and made diary ratings for each day. Results showed a variation in cortisol values between participants but also within individuals. After controlling for the individual differences, results showed that low cortisol levels in the morning were associated with sleepiness at awakening and anxiety, exhaustion, and poor health the day before. High evening levels of cortisol were associated with symptoms of stress and poor self-rated health. Further analysis of the cortisol awakening response (CAR) showed that all participants had a mixture of both a positive and negative responses. During mornings with a negative response participants stayed in bed for a longer time after the initial awakening, which might be a sign of snoozing, thus missing the awakening response.
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| 13. |
- Hillert, Lena, et al.
(author)
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The effects of 884 MHz GSM wireless communication signals on headache and other symptoms : an experimental provocation study.
- 2008
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In: Bioelectromagnetics. - : Wiley. - 1521-186X .- 0197-8462. ; 29:3, s. 185-96:Nov 28 [Epub ahead of print]
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Journal article (peer-reviewed)abstract
- The effects of 884 MHz GSM wireless communication signals on headache and other symptoms: an experimental provocation study.Hillert L, Akerstedt T, Lowden A, Wiholm C, Kuster N, Ebert S, Boutry C, Moffat SD, Berg M, Arnetz BB.Department of Public Health Sciences, Division of Occupational Medicine, Karolinska Institutet, Stockholm, Sweden. lena.hillert@ki.seFindings from prior studies of possible health and physiological effects from mobile phone use have been inconsistent. Exposure periods in provocation studies have been rather short and personal characteristics of the participants poorly defined. We studied the effect of radiofrequency field (RF) on self-reported symptoms and detection of fields after a prolonged exposure time and with a well defined study group including subjects reporting symptoms attributed to mobile phone use. The design was a double blind, cross-over provocation study testing a 3-h long GSM handset exposure versus sham. The study group was 71 subjects age 18-45, including 38 subjects reporting headache or vertigo in relation to mobile phone use (symptom group) and 33 non-symptomatic subjects. Symptoms were scored on a 7-point Likert scale before, after 1(1/2) and 2(3/4) h of exposure. Subjects reported their belief of actual exposure status. The results showed that headache was more commonly reported after RF exposure than sham, mainly due to an increase in the non-symptom group. Neither group could detect RF exposure better than by chance. A belief that the RF exposure had been active was associated with skin symptoms. The higher prevalence of headache in the non-symptom group towards the end of RF exposure justifies further investigation of possible physiological correlates. The current study indicates a need to better characterize study participants in mobile phone exposure studies and differences between symptom and non-symptom groups. (c) 2007 Wiley-Liss, Inc.
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| 14. |
- Ingre, Michael, et al.
(author)
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Sleep length as a function of morning shift-start time in irregular shift schedules for train drivers : self-rated health and individual differences.
- 2008
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In: Chronobiol Int. - : Informa UK Limited. - 1525-6073 .- 0742-0528. ; 25:2, s. 349-58
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Journal article (peer-reviewed)abstract
- Sleep length as a function of morning shift-start time in irregular shift schedules for train drivers: self-rated health and individual differences.Ingre M, Kecklund G, Akerstedt T, Söderström M, Kecklund L.Stress Research Institute, Stockholm University, Sweden. michael.ingre@stressforskning.su.seForty-six male train drivers (mean age = 46.5, SD = 5.1) were recruited to participate in a diary study for 14 consecutive days with questions about their sleep and working hours. A polynomial mixed-effect regression model showed a curvilinear relation ( p < .001) between shift-start time and sleep duration for shifts starting at 03:00-12:00 hand with a near linear increase for ones starting between 04:30 and 09:00 h of approximately 0.7 h for every 1 h the shift was delayed. The longest sleeps were estimated at approximately 8 h before shifts that started at approximately 10:00 h. The shortest sleeps were found for shifts that started before 04:30 h and were estimated at approximately 5 h. Individual differences were estimated with a random-effect standard deviation of 0.51 h, independent of shift start time ( p = .005). One-half of the between-subject variance was explained by subjective health. A one-step decrease in health was associated with a 26 min increase in sleep length. The results have practical implications for constructing shift schedules. Early morning shifts reduced sleep length substantially and should be mixed with later start hours to avoid the accumulation of sleep dept. Delaying the shift-start past 10:00 h had little effect on sleep opportunity; however, delaying shift-start to between 04:30 and 9:00 h had a strong impact on sleep length, with 70% of the extra time used for sleep, suggesting large positive effects for this range of shift-start times.
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| 15. |
- Kecklund, Göran, et al.
(author)
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Police officers attitude to different shift systems : Association with age, present shift schedule, health and sleep/wake complaints.
- 2008
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In: Appl Ergon. - : Elsevier BV. - 0003-6870. ; 39:5, s. 565-71
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Journal article (other academic/artistic)abstract
- Police officers attitude to different shift systems: Association with age, present shift schedule, health and sleep/wake complaints.Kecklund G, Eriksen CA, Akerstedt T.Stress Research Institute, Stockholm University, SE-106 91 Stockholm, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Sweden.It is often claimed that shift workers give priority to long series of days off and therefore prefer compressed work schedules at the expense of what is optimal for long-term health. The aim of the present study was to evaluate the attitude to six new shift systems among a randomly selected sample of police officers. The results showed that the most popular shift system was a rapidly, forward, rotating schedule with at least 16h of rest between shifts, despite that it had fewer days off compared with some of the compressed shift systems. However, the individual differences were large and many individuals (32%) disliked the rapidly rotating shift system. Young age was associated with a positive attitude to the rapidly rotating shift system. The attitude to the shift system was also influenced by the present schedule, and shift systems that were similar to the present work hours received more positive evaluation. Sleep and health complaints showed no association with the attitude to the shift systems. In conclusion, the shift workers attitude to the new schedules was partly in agreement with the ergonomic recommendations of the design of three-shift systems that will facilitate sufficient sleep and minimize negative health consequences.
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| 16. |
- Larsson, Anders, et al.
(author)
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Circadian variability of cystatin C, creatinine, and glomerular filtration rate (GFR) in healthy men during normal sleep and after an acute shift of sleep.
- 2008
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In: Chronobiol Int. - : Informa UK Limited. - 1525-6073 .- 0742-0528. ; 25:6, s. 1047-61
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Journal article (peer-reviewed)abstract
- Circadian variability of cystatin C, creatinine, and glomerular filtration rate (GFR) in healthy men during normal sleep and after an acute shift of sleep.Larsson A, Akerstedt T, Hansson LO, Axelsson J.Section of Clinical Chemistry, Department of Medical Sciences, Uppsala University, Uppsala, Sweden. anders.larsson@akademiska.seThe estimation of the glomerular filtration rate (GFR) is essential for the evaluation of patients with kidney disease and for the treatment of patients with medications that are eliminated by the kidneys. Plasma cystatin C has been shown in several studies to be superior to plasma creatinine for the estimation of GFR. However, there is limited information on the circadian variation of cystatin C and estimated GFR using cystatin C (eGFR(CystC)) or "The Modification of Diet in Renal Disease Study" (MDRD) (eGFR(MDRD)) equations. We studied the circadian variation of cystatin C and creatinine during night- and day-sleep conditions in seven healthy volunteers. Serum samples were collected every hour (48 samples per individual) to evaluate the effect of different sampling times on the test results. The median intra-individual coefficients of variations for the studied markers were 4.2% for creatinine, 4.7% for eGFR(MDRD), 5.5% for cystatin C, and 7.7% for eGFR(CystC). Neither cystatin C nor creatinine differed significantly between the night- and day-sleep conditions. Cystatin C differed significantly with time of day (p=.0003), but this was not the case for creatinine (p=.11). The circadian variation of cystatin C was minor. Small but significant increases in creatinine values and a decrease of eGFR(MDRD) were observed after food intake. Thus, cystatin C and creatinine sampling does not have to be restricted to specific times of the day.
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| 17. |
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| 18. |
- Lowden, Arne, et al.
(author)
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Wakefulness in young and elderly subjects driving at night in a car simulator.
- 2009
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In: Accident; analysis and prevention. - : Elsevier BV. - 1879-2057 .- 0001-4575. ; 41:5, s. 1001-7
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Journal article (peer-reviewed)abstract
- Young drivers are over-represented in nighttime traffic accidents and several studies have suggested that many accidents are associated with elevated sleepiness levels. It has been suggested that there may be a connection between lowered wake capacity and functional sensory motor skills on the one hand and sleep deprivation at the circadian low in young drivers on the other. Performance during a 45/min evening and night drive among young (n=10, age range 18-24 years) and elderly (n=10, age range 55-64 years) subjects was studied using a moving base driving simulator. EEG was measured continuously. Every 5 min, subjects were rated on the Karolinska Sleepiness Scale (KSS). Saliva cortisol was assessed before and after each drive. The results showed that sleepiness increased across each drive and was higher among young drivers at night. Relative EEG power increased among older drivers for frequencies of 10-16Hz. The sigma 1 frequency band (12-14Hz) proved particularly sensitive to sustained driving, and was elevated among subjects in the elderly group. Cortisol levels before and after the evening and night drive showed higher mean levels for elderly subjects. The present study has demonstrated that young drivers were more sleepy while driving at night. The effects could represent a mobilization of effort and a reorganization of brain firing pattern among older subjects, possibly reflecting better ability and effort to resist sleepiness.
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| 19. |
- Mallon, Lena, et al.
(author)
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Insomnia in Sweden : a population-based survey
- 2014
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In: Sleep Disorders. - : Hindawi Limited. - 2090-3545 .- 2090-3553. ; 2014, s. 843126-
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Journal article (peer-reviewed)abstract
- Aims. Estimate the prevalence of insomnia and examine effects of sex, age, health problems, sleep duration, need for treatment, and usage of sleep medication. Methods. A sample of 1,550 subjects aged 18-84 years was selected for a telephone interview. The interview was completed by 1,128 subjects (72.8%). Results. 24.6% reported insomnia symptoms. Insomnia disorder, that is, insomnia symptoms and daytime consequences, was reported by 10.5%. The prevalence was similar among all age groups, with the exception of women aged 40-49 years who demonstrated a significantly higher prevalence, 21.6%. Having at least one physical or psychiatric disorder was reported by 82.8% of subjects with insomnia disorder. Mean sleep duration for subjects with insomnia disorder was 5.77 hours on weeknights and 7.03 hours on days off/weekends. The corresponding figures for subjects without insomnia disorder were 7.04 hours and 7.86 hours, respectively. Among those with insomnia disorder 62.5% expressed a need for treatment, and 20.0% used prescribed sleep medication regularly. Conclusions. Insomnia disorder is highly prevalent in the population. There are significant associations between insomnia disorder and physical and psychiatric disorders. A majority of subjects with insomnia disorder expressed a need for treatment, indicating a public health problem.
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| 20. |
- Miley-Akerstedt, Anna, et al.
(author)
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Lifestyle Factors Are Important Contributors to Subjective Memory Complaints among Patients without Objective Memory Impairment or Positive Neurochemical Biomarkers for Alzheimer's Disease
- 2018
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In: Dementia and Geriatric Cognitive Disorders Extra. - : S. Karger AG. - 1664-5464. ; 8:3, s. 439-452
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Journal article (peer-reviewed)abstract
- Background/Aims: Many patients presenting to a memory disorders clinic for subjective memory complaints do not show objective evidence of decline on neuropsychological data, have nonpathological biomarkers for Alzheimer's disease, and do not develop a neurodegenerative disorder. Lifestyle variables, including subjective sleep problems and stress, are factors known to affect cognition. Little is known about how these factors contribute to patients' subjective sense of memory decline. Understanding how lifestyle factors are associated with the subjective sense of failing memory that causes patients to seek a formal evaluation is important both for diagnostic workup purposes and for finding appropriate interventions and treatment for these persons, who are not likely in the early stages of a neurodegenerative disease. The current study investigated specific lifestyle variables, such as sleep and stress, to characterize those patients that are unlikely to deteriorate cognitively. Methods: Two hundred nine patients (mean age 58 years) from a university hospital memory disorders clinic were included. Results: Sleep problems and having much to do distinguished those with subjective, but not objective, memory complaints and non-pathological biomarkers for Alzheimer's disease. Conclusions: Lifestyle factors including sleep and stress are useful in characterizing subjective memory complaints from objective problems. Inclusion of these variables could potentially improve health care utilization efficiency and guide interventions.
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| 21. |
- Persson, Roger, et al.
(author)
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Effects of the implementation of an 84-hour workweek on neurobehavioral test performance and cortisol responsiveness during testing.
- 2003
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In: Scandinavian Journal of Work, Environment and Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 29:4, s. 261-269
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Journal article (peer-reviewed)abstract
- OBJECTIVES: This study examined whether long workhours in combination with an extended workweek (12 hours/7 days), as requested by the workers, impaired attention and cognitive performance and whether the degree of hypothalamic-pituitary-adrenal (HPA) activation was related to the response to the performance tasks. METHODS: A group of 41 male construction workers between 21 and 60 (mean 39) years of age who worked 84 hours a week, with alternate weeks off, was compared with a group of 23 male construction workers between 24 and 65 (mean 43) years of age who had a traditional 40-hour work schedule. Neurobehavioral test performance, self-ratings of fatigue and sleepiness, and salivary cortisol levels were evaluated in a counterbalanced repeated-measures design. RESULTS: The 84-hour group did not show any signs of reduced test performance or elevated fatigue and sleepiness. The 84-hour group had faster reaction times on day 7 than on days 1 and 5. Although the expected activation of the HPA axis was only found in the total study sample when workdays 1 and 5 were collapsed, the HPA activation can be considered normal. CONCLUSIONS: The results suggest that an 84-hour work regimen in response to requests from workers does not induce more performance deficits than an ordinary 40-hour workweek. An extended work schedule of 84 hours cannot in the short-term be considered to affect basic mental capabilities negatively.
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| 23. |
- Söderström, Marie, et al.
(author)
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Weekday and weekend patterns of diurnal cortisol, activation and fatigue among people scoring high for burnout
- 2006
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In: SJWEH Supplements. - 1795-9926 .- 1795-9918. ; :2, s. 35-40:2, s. 35-40
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Journal article (peer-reviewed)abstract
- Objectives The present pilot study attempted to investigate the diurnal pattern of cortisol, subjective activation, and mental fatigue among workers scoring high for burnout. The purpose was also to relate the cortisol data to objective sleep data.Methods One group with high (N=9) burnout scores and one with low (N=11) such scores were compared during a workday and a day off.Results The high-burnout group showed higher awakening cortisol during the workday than during the weekend. They also showed higher ratings for activation and mental fatigue during the weekend than the low-burnout group. A higher frequency of arousals during the prior sleep was associated with a higher diurnal amplitude and an earlier diurnal peak of cortisol during the workday.Conclusions The present results, which, due to the small sample size, should be interpreted with caution, may indicate that stress-induced frequency of arousal during sleep could contribute to the diurnal amplitude of cortisol. Furthermore, increased activation and mental fatigue during the weekend may reflect impaired recovery, which is of possible importance in the burnout process.
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| 24. |
- Tholin, Sanna, et al.
(author)
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Prevalence of night eating in obese and nonobese twins.
- 2009
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In: Obesity (Silver Spring, Md.). - : Wiley. - 1930-7381. ; 17:5, s. 1050-5
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Journal article (peer-reviewed)abstract
- The aim of this study was to assess the prevalence of night eating (NE) and associated symptoms in a population-based sample of Swedish twins. A total of 21,741 individuals aged 20-47 years completed a questionnaire in 2005/2006. NE was defined as >/=25% of daily food intake after the evening meal and/or awakening at least once per week with eating episodes. The prevalence of NE was 4.6% in men and 3.4% in women. Among obese men and women, the prevalence was 8.4 and 7.5%, respectively. Men and women with NE had 3.4 and 3.6 times higher risk of binge eating compared to individuals without NE. The risk of sleep-related problems was 1.6-3.4 times higher in men and 2.5-3.3 times higher in women with NE compared to those without NE. This epidemiological study has estimated the prevalence of NE in a twin population. It revealed that NE is 2.5 and 2.8 times more common in obese men and women compared to normal weight men and women. Furthermore that NE is associated with binge eating and sleep-related problems.Obesity (2009) 17 5, 1050-1055. doi:10.1038/oby.2008.676.
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| 25. |
- Waage, Siri, et al.
(author)
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Shift work disorder among oil rig workers in the North Sea.
- 2009
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In: Sleep. - : Oxford University Press (OUP). - 0161-8105 .- 1550-9109. ; 32:4, s. 558-65
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Journal article (peer-reviewed)abstract
- STUDY OBJECTIVES: Shift work disorder (SWD) is a circadian rhythm sleep disorder caused by work hours during the usual sleep period. The main symptoms are excessive sleepiness and insomnia temporally associated with the working schedule. The aim of the present study was to examine SWD among shift workers in the North Sea. DESIGN AND PARTICIPANTS: A total of 103 shift workers (2 weeks on 7 nights/7days, 12-h shifts, 4 weeks off), mean age 39.8 years, working at an oil rig in the North Sea responded to a questionnaire about SWD. They also completed the Pittsburgh Sleep Quality Index, Bergen Insomnia Scale, Epworth Sleepiness Scale, Composite Morningness Questionnaire, Subjective Health Complaint Inventory, Demand/Control, and Instrumental Mastery Oriented Coping (based on the Utrecht Coping list). Most of these instruments were administered during the first day of the 2-week working period, thus reflecting symptoms and complaints during the 4-week non-work period. The shift workers were also compared to day workers at the oil rig. RESULTS: Twenty-four individuals were classified as suffering from SWD, yielding a prevalence for SWD of 23.3%. During the 4-week non-work period, individuals with SWD reported significantly poorer sleep quality, as measured by the Pittsburgh Sleep Quality Index, and more subjective health complaints than individuals not having SWD. There were no differences between the 2 groups in sleepiness, insomnia, circadian preference, psychological demands, or control. Individuals with SWD reported significantly lower scores on coping. The reports of shift workers without SWD were similar to those of day workers regarding sleep, sleepiness, subjective health complaints, and coping. CONCLUSIONS: The prevalence of SWD was relatively high among these shift workers. Individuals with SWD reported poorer sleep quality and more subjective health complaints in the non-work period than shift workers not having SWD.
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