Search

Summary: 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. [ABSTRACT FROM AUTHOR]

Summary: Previous work has shown that both long and short sleep duration is associated with increased mortality, with lowest risk around 7 hr. This has had widespread impact on views on the optimal sleep duration. However, age, being employed/retired, and blue‐/white‐collar status, may influence the time available for sleep and thus, confound the association. We investigated the role of these factors on the association between sleep duration and mortality. We used employed and retired participants (N = 25,430) from the Swedish National March Cohort and Cox proportional hazards regression to model the shape of the association. We found a significant U‐shaped association in a multivariable model with a hazard ratio (HR) of 1.24 (95% confidence interval [CI] 1.10, 1.39) for <5‐hr sleep duration, and a HR of 1.30 (95% CI 1.12, 1.51) for ≥9‐hr sleep duration, with the lowest HR for 7 hr, but with a span of low HRs from 5 to 8 hr. Unadjusted values showed a pronounced U‐shape. Adjusting for age accounted for most of the attenuation in the multivariable model. Stratification into five age groups showed a significant U‐shape only in those aged >60.3 years at baseline. The shape of the association did not differ between blue‐/white‐collar workers, nor between employed and retired groups. We conclude that the U‐shaped association between sleep duration and mortality is present only in older individuals. [ABSTRACT FROM AUTHOR]

Components of a healthy sleep pattern A particularly important contribution towards understanding the good sleep health behaviour measure is the sensitivity analysis looking at the link to mortality of each of the components of the index. Consequently, it has attracted a substantial amount of research during recent years, and a number of meta-analyses on sleep and health have been published [1-3] showing a U-shaped association, that is, both short sleep and a long sleep are associated with increased risk of premature death, but at rather modest levels, after adjustment for confounders. Sleep duration and mortality-does weekend sleep matter?. [Extracted from the article]

Summary: 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. [ABSTRACT FROM AUTHOR]

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

Women complain more about sleep than men, but polysomnography ( PSG) seems to suggest worse sleep in men. This raises the question of how women (or men) perceive objective ( PSG) sleep. The present study sought to investigate the relation between morning subjective sleep quality and PSG variables in older and younger women. A representative sample of 251 women was analysed in age groups above and below 51.5 years (median). PSG was recorded at home during one night. Perceived poor sleep was related to short total sleep time ( TST), long wake within total sleep time ( WTSP), low sleep efficiency and a high number of awakenings. The older women showed lower TST and sleep efficiency and higher WTSP for a rating of good sleep than did the younger women. For these PSG variables the values for good sleep in the older group were similar to the values for poor sleep in the young group. It was concluded that women perceive different levels of sleep duration, sleep efficiency and wake after sleep onset relatively well, but that older women adjust their objective criteria for good sleep downwards. It was also concluded that age is an important factor in the relation between subjective and objective sleep. [ABSTRACT FROM AUTHOR]

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

SummaryIn view of reports of health problems induced by low frequency (50–60Hz) electromagnetic fields (EMF), we carried out a study in 18 healthy subjects, comparing sleep with and without exposure to a 50Hz/1μTesla electrical field. We found that the EMF condition was associated with reduced: total sleep time (TST), sleep efficiency, stages 3+4 slow wave sleep (SWS), and slow wave activity (SWA). Circulating melatonin, growth hormone, prolactin, testosterone or cortisol were not affected. The results suggest that commonly occurring low frequency electromagnetic fields may interfere with sleep. [ABSTRACT FROM AUTHOR]

This study explores the prevalence of attributed causes of disturbed sleep and the association between stress‐disturbed sleep and age, sex, and sleep duration on weekdays as well as weekends in a representative sample. A nationally representative sample (n = 1,128, response rate 72.8%), stratified for sex and age, completed a computer‐assisted phone survey that included questions about sleep disturbances and attributed causes. Stress was the main attributed cause of sleep disturbance (35.1%), most frequently attributed by younger women (χ2 = 26.5, p < 0.001). Prevalence of stress‐disturbed sleep was higher with lower age (B = −0.05, odds ratio (OR) = 0.94, CI = 0.91, 0.98). There was a trend, however, toward a significant interaction between age and sex, with women in the older age‐groups more frequently reporting stress‐disturbed sleep than older men (B = −0.02, OR = 1.022, CI = 1.003, 1.042). Weekday sleep duration decreased with increased stress‐disturbed sleep, with an inverse relationship on weekends except for those reporting stress‐disturbed sleep more than 5 days per week (F = 10.5, p < 0.001), who also had the shortest weekend sleep duration. Sleep disturbances were commonly attributed to stress, and more strongly so in women younger than 46 years. Stress‐disturbed sleep during weekdays seems to be potentially compensated for with extended sleep on weekends, except for those with continuous stress‐disturbed sleep. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective: Environmental factors play a prominent role in multiple sclerosis (MS) etiology. The aim of this study was to investigate the potential association between shift work and MS risk, which has previously never been investigated. Methods: This report is based on 2 population-based, case-control studies, 1 with incident cases (1,343 cases, 2,900 controls) and 1 with prevalent cases (5,129 cases, 4,509 controls). Using logistic regression, the occurrence of MS among subjects who have been exposed to shift work at various ages was compared with that of those who have never been exposed by calculating the odds ratio (OR) with a 95% confidence interval (CI). Results: In both studies, there was a significant association between working shift at a young age and occurrence of MS (OR, 1.6; 95% CI, 1.2-2.1 in the incidence study and OR, 1.3; 95% CI, 1.0-1.6 in the prevalence study). In the incident study, the OR of developing MS was 2.0 (95% CI, 1.2-3.6) among those who had worked shifts for 3 years or longer before age 20 years, compared with those who had never worked shifts. The OR for the corresponding comparison in the prevalent study was 2.1 (95% CI, 1.3-3.4). Interpretation: The observed association between shift work at a young age and occurrence of MS in 2 independent studies strengthens the notion of a true relationship. Consequences of shift work such as circadian disruption and sleep restriction are associated with disturbed melatonin secretion and enhanced proinflammatory responses and may thus be part of the mechanism behind the association. ANN NEUROL 2011; [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The present study of sleepiness and accident risk in a HI-FI car simulator aimed to provide subject-level relative risks (RR) with 95% confidence intervals (CI) for different levels of subjective sleepiness measured with the Karolinska Sleepiness Scale (KSS), 1 = very alert, 9 = very sleepy, fighting sleep, an effort to staying awake. Five male and five female shift workers, mean age 37 years, participated with a 2-h drive (08:00–10:00 hours) in a dynamic high-fidelity moving base driving simulator, after a night of work and after a night of sleep. Subjective sleepiness was measured with KSS every 5 min and events of incidents (two wheels outside the right lane), accidents (two wheels off the road or four wheels in opposite lane) and crashes (four wheels off the road) were recorded. The probability of an accident was modelled with a Generalized Linear Mixed Model approach to estimate subject-specific effects, rather than group average effects, to avoid the ecological fallacy. The results showed that sleepiness was strongly related to accident risk. An average subject was estimated at 28.2 times (95% CI RR = 10.7–74.1) increased risk at KSS = 8 and at 185 times (95% CI RR = 42–316) at KSS = 9 compared with KSS = 5. There were large individual differences in event propensity that complicates the prediction of absolute accident risk for individual subjects. [ABSTRACT FROM AUTHOR]

The present study aimed to provide subject-specific estimates of the relation between subjective sleepiness measured with the Karolinska Sleepiness Scale (KSS) and blink duration (BLINKD) and lane drifting calculated as the standard deviation of the lateral position (SDLAT) in a high-fidelity moving base driving simulator. Five male and five female shift workers were recruited to participate in a 2-h drive (08:00–10:00 hours) after a normal night sleep and after working a night shift. Subjective sleepiness was rated on the KSS in 5-min intervals during the drive, electro-occulogram (EOG) was measured continuously to calculate BLINKD, and SDLAT was collected from the simulator. A mixed modelanova showed a significant ( P < 0.001) effect of the KSS for both dependent variables. A test for a quadratic trend suggests a curvilinear effect with a steeper increase at high KSS levels for both SDLAT ( P < 0.001) and BLINKD ( P = 0.003). Large individual differences were observed for the intercept ( P < 0.001), suggesting that subjects differed in their overall driving performance and blink duration independent of sleepiness levels. The results have implications for any application that needs prediction at the subject level (e.g. driver fatigue warning systems) as well as for research design and the interpretation of group average data. [ABSTRACT FROM AUTHOR]

Driving in the early morning is associated with increased accident risk affecting not only professional drivers but also those who commute to work. The present study used a driving simulator to investigate the effects of driving home from a night shift. Ten shift workers participated after a normal night shift and after a normal night sleep. The results showed that driving home from the night shift was associated with an increased number of incidents (two wheels outside the lane marking, from 2.4 to 7.6 times), decreased time to first accident, increased lateral deviation (from 18 to 43 cm), increased eye closure duration (0.102 to 0.143 s), and increased subjective sleepiness. The results indicate severe postnight shift effects on sleepiness and driving performance. [ABSTRACT FROM AUTHOR]

Night work is non-optimal for performance and recuperation because of a lack of circadian influence that fully promote a night orientation. Our study assessed, in an industrial setting, the effects of bright light exposure (BL) on sleepiness, sleep and melatonin, during night work and during the following readaptation to day work. In a crossover design, 18 workers at a truck production plant were exposed to either BL (2500 lx) during breaks or normal light during four consecutive weeks. Twenty minute breaks were initiated by 67% of the workers between 03:00 and 04:00 hours. Sleep/wake patterns were assessed through actigraphs and ratings were given in a sleep/wake diary. Saliva melatonin was measured at 2-h intervals before, during and after night shift weeks. A significant interaction demonstrated a reduction of sleepiness in the BL condition particularly on the first two nights at 04:00 and 06:00 hours. Day sleep in the BL condition was significantly lengthened. Bright light administration significantly suppressed melatonin levels during night work and most strongly at 02:00 hours. Daytime melatonin during the readaptation after night work remained unaffected. The present findings demonstrate the feasibility and benefits of photic stimulation in industrial settings to increase adaptation to night work. [ABSTRACT FROM AUTHOR]

The present study sought to investigate the effects of lifetime accumulated night work on subjective health and sleep in monozygotic twins discordant on the exposure to night work. A total of 169 twin pairs (83 males, 86 females) over 65 years of age were analyzed on variables that describe the presence or absence of complaints regarding subjective health, disturbed sleep, repeated awakenings and not being well rested. Significant ( P < 0.05) risk ratios (RR) were found for subjective health (RR = 1.67) and disturbed sleep (RR = 2.83) indicating a higher risk of developing complaints to former night workers. There was neither a dose-dependent effect of night work nor an interaction effect with gender observed. [ABSTRACT FROM AUTHOR]

Accident register data, time budget studies and road traffic flow data were used to compute the age and gender-dependent relative risk [odds ratio (OR)] of being involved in a driving accident in which the driver was injured or killed. Alcohol-related accidents were excluded from the analysis. The results showed that the night-time risk, compared with that of the forenoon, was dramatically increased (OR=5) for young drivers (18–24 years) and reduced for old (65+) drivers. In direct comparison, the young drivers had 5–10 times higher risk of being involved in an accident during late night than during the forenoon, with the excess risk during the daytime being considerably lower. Women had a less pronounced night-time peak than men. In direct comparison, men had twice as high a risk as women during the late night hours. The results clearly demonstrate a strong effect of young age on night-time accident risk, together with a moderate effect of (male) gender. [ABSTRACT FROM AUTHOR]

SummaryThe present study describes the spontaneous sleep/wake pattern in connection with an eastward (Stockholm to Tokyo,+8 h) transmeridian flight and short (51 h) layovers. To describe all sleep episodes and the recovery process across 4 days, and to relate adjustment to individual differences, 49 Scandinavian Airlines System (SAS) air crew were monitored for 9 days with activity monitors and sleep/wake diary before-during-after flight. The outbound flight involved a period of wakefulness extended to 21 h, frequently (87% of air crew) terminated by a long nap in Tokyo which was calm but difficult to wake up from. Then followed two night oriented sleep periods of normal length but of reduced efficiency, containing many and long awakenings. Napping was common during the extended periods of wakefulness, particularly during flights. During the recovery days, ease of rising from sleep in the mornings was difficult throughout, and feelings of not being refreshed returned to baseline levels on the third recovery sleep. Elevated daytime sleepiness (24% of the day) was observed on the first recovery day. No individual differences related to gender, age or position (cabin/pilot) was found in sleep strategy. Poor adjusters, subjects with a perceived lowered capacity on recovery days, showed more premature awakenings abroad and less refreshing sleep during the last 12 months, suggesting a decreased ability to cope with air crew scheduling. Comparisons with a westbound flight showed the eastbound flight layover sleep to be more problematic and containing more napping. [ABSTRACT FROM AUTHOR]

This paper presents a modification of the quantitative "three-process model of alertness regulation" to predict sleep latency in connection with irregular sleep/wake patterns. This model uses a circadian and a homeostatic component(sleep loss) that are summed to yield predicted alertness (on a scale of 1 to 20) across a specified time span. The timing of sleep from two studies of irregular sleep were used as input to the model. The predicted alertness at bedtime was regressed on empirical sleep latency from two studies. The maximum R[SUP2] (0.88) was reached for an exponential function, with the model acrophase set to 2048. The predictions were cross validated on another set of sleep latency data from an irregular sleep study and a maximum R[SUP2] of 0.65 was obtained. In both studies, the prediction from the model explained more variance that did self-rated alertness at bedtime. Cross validation was also carried out successfully with published data from two studies of shift work. It was concluded that sleep latency on irregular schedules may be predicted with accuracy from knowledge of the prior sleep/wake pattern. This may have practical consequences for rest/activity management. [ABSTRACT FROM AUTHOR]

Recent concepts of sleep/wake regulation have emphasized circadian influences and largely disregarded homeostatic ones. The present experiment was designed to study sleep loss homeostasis while minimizing confounding circadian influences. Eight male subjects participated in the study. Night sleep was curtailed across four conditions to yield 0, 2, 4, or 8 hrs of sleep. The effects were studied on subsequent day sleep begun at 1100h and spontaneously terminated. Total sleep time (TST), Stage 2 (S2), and Stages 3 + 4 (SWS) showed very strong dose-dependent increases with increasing loss. REM sleep did not respond. After maximum sleep loss TST and S2 doubled whereas SWS increased fivefold. Sleep did not terminate until the prior loss of SWS had been recovered. The total SWS recovery approximately matched the loss. TST, S2, and REM failed to recover more than limited amounts of the loss. The results show that homeostatic influences on sleep may be much larger than usually acknowledged and that SWS closely, although not perfectly, reflects the "active component" of sleep homeostasis. [ABSTRACT FROM AUTHOR]

Twelve subjects were kept awake 64 hrs. During baseline and recovery sleep, subjects were given a simple memory task. The subjects were awakened 3 times each night during slow-wave sleep and shown 4 playing cards. Approximately 90 mm later the subjects were again awakened and tested for retention of the previous cards and given 4 new cards to learn. This procedure was repeated 3 times each night and upon awakening the following morning. On the recovery night recall was reduced, slow-wave sleep was lengthened, sleep latency was shortened, and body motility was reduced. It was suggested that the reason for the poorer recall was deeper sleep induced by the sleep deprivation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Summary: 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. [ABSTRACT FROM AUTHOR]

Summary: Sleep restriction therapy is a central component of cognitive behavioural therapy for insomnia, but can lead to excessive sleepiness, which may impede treatment adherence. Sleep compression therapy has been suggested as a possibly gentler alternative. The aim of this study was to compare the effects of sleep restriction therapy and sleep compression therapy on objective measures of sleep, with a focus on magnitude and timing of effects. From a larger study of participants with insomnia, a sub‐sample of 36 underwent polysomnographic recordings, before being randomised to either sleep restriction (n = 19) or sleep compression (n = 17) and receiving online treatment for 10 weeks. Assessments with polysomnography were also carried out after 2, 5, and 10 weeks of treatment. Data were analysed with multilevel linear mixed effect modelling. As per treatment instructions, participants in sleep restriction initially spent shorter time in bed compared with sleep compression. Participants in sleep restriction also showed an initial decrease of total sleep time, which was not seen in the sleep compression group. Both treatments led to improvements in sleep continuity variables, with a tendency for the improvements to come earlier during treatment in sleep restriction. No substantial differences were found between the two treatments 10 weeks after the treatment start. The results indicate that homeostatic sleep pressure may not be as important as a mechanism in sleep compression therapy as in sleep restriction therapy, and an investigation of other mechanisms is needed. In conclusion, the treatments led to similar changes in objective sleep at a somewhat different pace, and possibly through different mechanisms. [ABSTRACT FROM AUTHOR]

Background: Insomnia is common in Tourette syndrome (TS) and chronic tic disorder (CTD), but precise prevalence estimates are lacking. Objective: In this Swedish register‐based cohort study, we estimated the prevalence of insomnia in TS/CTD and quantified the magnitude of this association, accounting for familial confounders and relevant somatic and psychiatric comorbidities. Methods: Of 10,444,702 individuals living in Sweden during the period from 1997 to 2013, 5877 had a diagnosis of TS/CTD and were compared to unexposed individuals from the general population on the presence of insomnia using logistic regression models. Results: Individuals with TS/CTD had a period prevalence of insomnia of 32.16%, compared to 13.70% of the unexposed population. This translated into a 6.7‐fold increased likelihood of insomnia in TS/CTD (odds ratio adjusted [aOR] for sex, birth year, birth country, and somatic disorders = 6.74; 95% confidence interval [CI], 6.37–7.15). A full sibling comparison, designed to adjust for shared familial factors, attenuated the estimates (aOR = 5.41; 95% CI, 4.65–6.30). When individuals with attention‐deficit/hyperactivity disorder (ADHD) and pervasive developmental disorders were excluded, the association was also attenuated, whereas exclusion of other psychiatric comorbidities had minimal impact. Having persistent TS/CTD, comorbid ADHD, and taking ADHD medication greatly increased the likelihood of insomnia. Conclusions: Insomnia is significantly associated with TS/CTD, independently from somatic disorders, familial factors or psychiatric comorbidities, although familial factors, neurodevelopmental comorbidities, and ADHD/ADHD medication may explain part of the association. Insomnia should be routinely assessed and managed in TS/CTD, particularly in chronic patients and in those with comorbid ADHD. Other sleep disorders require further study. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Objective: To investigate how playing a violent/nonviolent television game during the evening affects sympathetic and parasympathetic reactions during and after playing as well as sleep quality during the night after playing. Subjects and Methods: In total, 19 boys, 12–15 years of age, played television games on two occasions in their homes and participated once without gaming. Heart rate, heart rate variability (HRV) and physical activity were measured during gaming/participating and the night to follow using a portable combined heart rate and movement sensor. A sleep diary and questionnaires about gaming experiences and session-specific experiences were filled in. Criteria for Selection of Games: Violent game involves/rewards direct physical violence (no handguns) against another person, and nonviolent game involves/rewards no violence; same game design (‘third-person game’); conducted in the same manner; no differences concerning motor activity; similar sound and light effects; no sexual content, violence against women or racial overtones. Results: During violent (vs. nonviolent) gaming, there was significantly higher activity of the very low frequency component of the HRV and total power. During the night after playing, very low frequency, low frequency and high frequency components were significantly higher during the violent (vs. nonviolent) condition, just as total power. There were no significant differences between the three conditions (violent/nonviolent/no gaming) with respect to an index reflecting subjectively perceived sleep difficulties. Nor was there any difference between violent and nonviolent condition for any single sleep item. Conclusion: Violent gaming induces different autonomic responses in boys compared to nonviolent gaming – during playing and during the following night – suggesting different emotional responses. Subjectively perceived sleep quality is not influenced after a single gaming experience. Future studies should address the development of the autonomic balance after gaming over longer time than a night, physiological adaptation to frequent gaming and potential gender differences. [ABSTRACT FROM AUTHOR]

Understanding the association between autonomic nervous system [ANS] function and brain morphology across the lifespan provides important insights into neurovisceral mechanisms underlying health and disease. Resting‐state ANS activity, indexed by measures of heart rate [HR] and its variability [HRV] has been associated with brain morphology, particularly cortical thickness [CT]. While findings have been mixed regarding the anatomical distribution and direction of the associations, these inconsistencies may be due to sex and age differences in HR/HRV and CT. Previous studies have been limited by small sample sizes, which impede the assessment of sex differences and aging effects on the association between ANS function and CT. To overcome these limitations, 20 groups worldwide contributed data collected under similar protocols of CT assessment and HR/HRV recording to be pooled in a mega‐analysis (N = 1,218 (50.5% female), mean age 36.7 years (range: 12–87)). Findings suggest a decline in HRV as well as CT with increasing age. CT, particularly in the orbitofrontal cortex, explained additional variance in HRV, beyond the effects of aging. This pattern of results may suggest that the decline in HRV with increasing age is related to a decline in orbitofrontal CT. These effects were independent of sex and specific to HRV; with no significant association between CT and HR. Greater CT across the adult lifespan may be vital for the maintenance of healthy cardiac regulation via the ANS—or greater cardiac vagal activity as indirectly reflected in HRV may slow brain atrophy. Findings reveal an important association between CT and cardiac parasympathetic activity with implications for healthy aging and longevity that should be studied further in longitudinal research. Impact Statement: Understanding which brain areas are associated with autonomic function has important clinical implications. Previous research was limited to small samples. Aiming for a thorough and large replication, we investigated n = 1,218 healthy subjects in a pooled mega‐analysis. We found unique associations between vagal activity and cortical thickness of frontal brain areas. It is suggested that greater integrity of prefrontal brain areas may be vital for the maintenance of adaptive autonomic nervous system activity in aging. [ABSTRACT FROM AUTHOR]

SummaryNight workers complain of sleepiness, reduced performance and disturbed sleep due to lack of adjustment of the circadian rhythm. In simulated night-work experiments scheduled exposure to bright light has been shown to reduce these complaints. Here we studied the effects of bright light treatment on the adaptation to 14 days of consecutive night work at an oil platform in the North Sea, and the subsequent re-adaptation to day life at home, using the Karolinska sleep/wake diary. Bright light treatment of 30 min per exposure was applied during the first 4 nights of the night-shift period and the first 4 days at home following the shift period. The bright light exposure was scheduled individually to phase delay the circadian rhythm. Bright light treatment modestly facilitated the subjective adaptation to night work, but the positive effect of bright light was especially pronounced during the re-adaptation back to day life following the return home. Sleepiness was reduced and the quality of day was rated better after exposure to bright light. The modest effect of bright light at the platform was, possibly, related to the finding that the workers seemed to adapt to night work within a few days even without bright light. These results suggest that short-term bright light treatment may help the adaptation to an extended night-work period, and especially the subsequent re-adaptation to day life. [ABSTRACT FROM AUTHOR]

The use of a short (< 1 h) nap in improving alertness during the early morning hours in the first night shift was examined under laboratory conditions. The study contained four experimental, non-consecutive night shifts with a nap of either 50 or 30 min at 01.00 or 04.00 hours. An experimental night shift without a nap served as a control condition. Each experimental shift was followed by daytime sleep. Fourteen experienced male shift workers went through all of the experimental conditions. The results showed that the naps improved the ability to respond to visual signals during the second half of the night shift. Physiological sleepiness was alleviated by the early naps, as measured 50 min after awakening, but not at the end of the shift. Subjective sleepiness was somewhat decreased by the naps. The naps produced sleep inertia which lasted for about 10–15 min. Daytime sleep was somewhat impaired by the 50 min naps. The study shows that a nap shorter than 1 h is able to improve alertness to a certain extent during the first night shift. [ABSTRACT FROM AUTHOR]

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

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

Potential long‐term consequences of hypnotics remain controversial. We used the prospective Swedish National March Cohort, a study based on 41,695 participants with a mean follow‐up duration of 18.9 years. Logistic regression models and Cox proportional hazards models with attained age as timescale were used to assess associations of hypnotic use with short‐ and long‐term mortality. The proportion of subjects who initiated or discontinued hypnotic use during follow‐up was substantial. All groups of hypnotics were associated with increased mortality within 2 years after a first prescription, with an overall OR of 2.38 (95% CI, 2.13–2.66). The association was more pronounced among subjects younger than 60 years (OR, 6.16; 95% CI, 3.98–9.52). There was no association between hypnotic use and long‐term mortality. The association between hypnotic use and increased mortality was thus restricted to a relatively short period after treatment initiation, and may be explained in terms of confounding by indication. [ABSTRACT FROM AUTHOR]

Studies on sleep after exposure to radiofrequency electromagnetic fields have shown mixed results. We investigated the effects of double‐blind radiofrequency exposure to 1,930–1,990 MHz, UMTS 3G signalling standard, time‐averaged 10 g specific absorption rate of 1.6 W kg−1 on self‐evaluated sleepiness and objective electroencephalogram architecture during sleep. Eighteen subjects aged 18–19 years underwent 3.0 hr of controlled exposure on two consecutive days 19:45–23:00 hours (including 15‐min break); active or sham prior to sleep, followed by full‐night 7.5 hr polysomnographic recordings in a sleep laboratory. In a cross‐over design, the procedure was repeated a week later with the second condition. The results for sleep electroencephalogram architecture showed no change after radiofrequency exposure in sleep stages compared with sham, but power spectrum analyses showed a reduction of activity within the slow spindle range (11.0–12.75 Hz). No differences were found for self‐evaluated health symptoms, performance on the Stroop colour word test during exposure or for sleep quality. These results confirm previous findings that radiofrequency post‐exposure in the evening has very little influence on electroencephalogram architecture but possible on spindle range activity. [ABSTRACT FROM AUTHOR]

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

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

The weekend is usually seen as a window of recovery. Thus, sleep before a day off may be less impaired than that before a workday. However, very few polysomnographical studies have investigated this hypothesis. Therefore, the aim of the present study was to compare sleep before a workday with that before a weekend. Seventeen teachers participated. Sleep was recorded with polysomnography on one weekday night during the workweek, and on a workday (Friday) followed by a day off. Sleep diaries and actigraphs were also used. Weekend sleep showed delayed bedtime and time of rising, a longer total sleep time (45 min), increased N3 and N1, and decreased N2 and REM. Sleep spindles were reduced. The results remained after truncation to the shortest common sleep duration (5 h). The increase in N3 from weekday sleep to Friday night sleep was positively correlated with N1 change ( r = 0.853, P ≤ 0.001), and negatively correlated with N2 change ( r = −0.614, P ≤ 0.001). Subjective ratings showed that weekend sleep was associated with less awakening problems and lower subjective arousal during the day. The authors concluded that weekend sleep was longer, and showed increased N3 and N1. The authors suggest that the N3 increase before the day off is a result of lower stress, while the N1 increase may be an effect of sleep spindle suppression via the increase of N3 (which would suppress sleep spindles), thus reducing N2 and enhancing N1. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article about the association of playing a violent television game to saliva cortisol in the October 28, 2008 issue.

The European Sleep Research Society aimed to estimate the prevalence, determinants and consequences of falling asleep at the wheel. In total, 12 434 questionnaires were obtained from 19 countries using an anonymous online questionnaire that collected demographic and sleep-related data, driving behaviour, history of drowsy driving and accidents. Associations were quantified using multivariate logistic regression. The average prevalence of falling asleep at the wheel in the previous 2 years was 17%. Among respondents who fell asleep, the median prevalence of sleep-related accidents was 7.0% (13.2% involved hospital care and 3.6% caused fatalities). The most frequently perceived reasons for falling asleep at the wheel were poor sleep in the previous night (42.5%) and poor sleeping habits in general (34.1%). Falling asleep was more frequent in the Netherlands [odds ratio = 3.55 (95% confidence interval: 1.97; 6.39)] and Austria [2.34 (1.75; 3.13)], followed by Belgium [1.52 (1.28; 1.81)], Portugal [1.34 (1.13, 1.58)], Poland [1.22 (1.06; 1.40)] and France [1.20 (1.05; 1.38)]. Lower odds were found in Croatia [0.36 (0.21; 0.61)], Slovenia [0.62 (0.43; 0.89)] and Italy [0.65 (0.53; 0.79)]. Individual determinants of falling asleep were younger age; male gender [1.79 (1.61; 2.00)]; driving ≥20 000 km year [2.02 (1.74; 2.35)]; higher daytime sleepiness [7.49 (6.26; 8.95)] and high risk of obstructive sleep apnea syndrome [3.48 (2.78; 4.36) in men]. This Pan European survey demonstrates that drowsy driving is a major safety hazard throughout Europe. It emphasizes the importance of joint research and policy efforts to reduce the burden of sleepiness at the wheel for European drivers. [ABSTRACT FROM AUTHOR]

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

The purpose of this study was to investigate if and how sleep physiology is affected by naturally occurring high work stress and identify individual differences in the response of sleep to stress. Probable upcoming stress levels were estimated through weekly web questionnaire ratings. Based on the modified FIRST-scale (Ford insomnia response to stress) participants were grouped into high ( n = 9) or low ( n = 19) sensitivity to stress related sleep disturbances (Drake et al., 2004). Sleep was recorded in 28 teachers with polysomnography, sleep diaries and actigraphs during one high stress and one low stress condition in the participants home. EEG showed a decrease in sleep efficiency during the high stress condition. Significant interactions between group and condition were seen for REM sleep, arousals and stage transitions. The sensitive group had an increase in arousals and stage transitions during the high stress condition and a decrease in REM, whereas the opposite was seen in the resilient group. Diary ratings during the high stress condition showed higher bedtime stress and lower ratings on the awakening index (insufficient sleep and difficulties awakening). Ratings also showed lower cognitive function and preoccupation with work thoughts in the evening. KSS ratings of sleepiness increased during stress for the sensitive group. Saliva samples of cortisol showed no effect of stress. It was concluded that moderate daily stress is associated with a moderate negative effect on sleep sleep efficiency and fragmentation. A slightly stronger effect was seen in the sensitive group. [ABSTRACT FROM AUTHOR]

This study investigated the effects of two very commonly used countermeasures against driver sleepiness, opening the window and listening to music, on subjective and physiological sleepiness measures during real road driving. In total, 24 individuals participated in the study. Sixteen participants received intermittent 10-min intervals of: (i) open window (2 cm opened); and (ii) listening to music, during both day and night driving on an open motorway. Both subjective sleepiness and physiological sleepiness (blink duration) was estimated to be significantly reduced when subjects listened to music, but the effect was only minor compared with the pronounced effects of night driving and driving duration. Open window had no attenuating effect on either sleepiness measure. No significant long-term effects beyond the actual countermeasure application intervals occurred, as shown by comparison to the control group ( n = 8). Thus, despite their popularity, opening the window and listening to music cannot be recommended as sole countermeasures against driver sleepiness. [ABSTRACT FROM AUTHOR]

The 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. [ABSTRACT FROM AUTHOR]

Elite athletes and their coaches are accustomed to international travel for purposes of training or sports competition. Recreational participants are similarly, if less frequently, exposed to travel stress. Transient negative effects that constitute travel fatigue are quickly overcome, whereas longer-lasting difficulties are associated with crossing multiple time-zones. Jet-lag is linked with desynchronization of circadian rhythms, and its impact depends on the duration and direction of flight, flight schedule, and individual differences. Athletes' performances are likely to be affected for some days until the body clock is readjusted in harmony with local time. Knowledge of the physiological characteristics of the body clock can be used to develop behavioural strategies that accelerate readjustment, in particular the timing of outdoor or bright light exposure, perhaps melatonin ingestion, meals, and exercise. Attempts to promote sleep by use of drugs that adjust the body clock, induce sleepiness or promote wakefulness are relevant but discouraged in travelling athletes. Support staff should develop appropriate education programmes for their athletes who can then make informed choices about their behaviour and minimize the transient effects of jet-lag on their well-being and performance. [ABSTRACT FROM AUTHOR]

Sleep deprivation commonly impairs affective regulation and causes worse mood. However, the majority of previous research concerns young adults. Because susceptibility to sleep deprivation and emotion regulation change distinctively across adult age, we tested here the hypothesis that the effect of sleep deprivation on mood is stronger in young than in older adults. In an experimental design, young (18–30 years) and older adults (60–72 years) participated in either a sleep control (young, n = 63; older, n = 47) or a total sleep deprivation condition (young, n = 61; older, n = 47). Sleepiness, mood and common symptoms of sleep deprivation were measured using established questionnaires and ratings. Sleep‐deprived participants felt more sleepy, stressed and cold, and reported lower vigour and positive affect, regardless of age. All the other outcome measures (negative affect, depression, confusion, tension, anger, fatigue, total mood disturbance, hunger, cognitive attenuation, irritability) showed a weaker response to sleep deprivation in the older group, as indicated by age*sleep deprivation interactions (ps < 0.05). The results show that older adults are emotionally less affected by sleep deprivation than young adults. This tolerance was mainly related to an attenuated increase in negative mood. This could possibly be related to the well‐known positivity effect, which suggests that older adults prioritize regulating their emotions to optimize well‐being. The results also highlight that caution is warranted when generalizing results from sleep deprivation studies across the adult lifespan. [ABSTRACT FROM AUTHOR]

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