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INTRODUCTION:Many sleep and circadian studies require participants to adhere to structured sleep-wake schedules designed to stabilize sleep outcomes and circadian phase prior to in-laboratory testing. The effectiveness of this approach has not been rigorously evaluated, however. We therefore investigated the differences between participants' unstructured and structured sleep over a three-week interval. METHODS:Twenty-three healthy young adults completed three weeks of sleep monitoring, including one week of unstructured sleep and two weeks of structured sleep with consistent bed and wake times. Circadian phase was assessed via salivary dim light melatonin onset (DLMO) during both the unstructured and structured sleep episodes. RESULTS:Compared to their unstructured sleep schedule, participants' bed- and wake times were significantly earlier in their structured sleep, by 34 ± 44 mins (M ± SD) and 44 ± 41 mins, respectively. During structured sleep, circadian phase was earlier in 65% of participants (40 ± 32 mins) and was later in 35% (41 ± 25 mins) compared to unstructured sleep but did not change at the group level. While structured sleep reduced night-to-night variability in sleep timing and sleep duration, and improved the alignment (phase angle) between sleep onset and circadian phase in the most poorly aligned individuals (DLMO < 1h or > 3h before sleep onset time; 25% of our sample), sleep duration and quality were unchanged. CONCLUSION:Our results show adherence to a structured sleep schedule results in more regular sleep timing, and improved alignment between sleep and circadian timing for those individuals who previously had poorer alignment. Our findings support the use of structured sleep schedules prior to in-laboratory sleep and circadian studies to stabilize sleep and circadian timing in healthy volunteers.

Introduction Parents are vulnerable to psychological distress symptoms in the postpartum period. It is routine to screen for depressive symptoms, but anxiety, stress, fatigue, irritability and insomnia symptoms are less often assessed despite their prevalence. This study aimed to assess multiple dimensions of psychological distress, and their reliable change and clinically significant change among women admitted to a residential program for assistance with unsettled infant behaviors (UIB). Method Women admitted to a five-night residential early parenting program completed self-report measures: the Depression Anxiety Stress Scale, Irritability Depression Anxiety Scale, Fatigue Severity Scale, and Insomnia Severity Index. A sub-group completed a computerized emotional Go-NoGo (EGNG) task as a measure of emotional impulsivity. Results Seventy-eight women were recruited (Mage = 34.46, SDage = 4.16). On admission, 48% of women reported clinically elevated depressive symptoms and 97.5% of women not reporting elevated depressive symptoms reported clinical elevations in at least one other form of distress. Upon discharge, all self-report distress symptoms were significantly reduced (all p-values

The public expects firefighters to be available around-the-clock and to perform flawlessly when called upon. The majority of career firefighters work 24-hour extended-duration shifts, which cause acute sleep deprivation, chronic sleep deficiency, and circadian misalignment.1 The negative consequences of sleep loss are of major concern to firefighters2 and more than half of firefighters report sleep disturbances.3 In addition, a significant proportion of firefighters suffer from undiagnosed sleep disorders, which further impair sleep and exacerbate fatigue.4 Sleep deficiency and sleep disorders are associated with an increased risk of crashes, injuries, and adverse mental and physical health outcomes,3–8 including a greatly increased risk of motor vehicle crashes and heart attacks, the two leading causes of death in firefighters.9 In addition, the annual direct costs to the United States from sleep disorders and sleepiness are estimated to be in excess of 15 billion dollars, and total costs including lost productivity may exceed 150 billion dollars.10 The total cost of accidents due to sleepiness has been estimated to be between 43 and 56 billion dollars.11 Fatigue education and awareness training programs are required in commercial aviation12 and similar programs have been instituted successfully for railroad workers,13 truckers,14 and nurses.15,16 Recently, we developed a sleep health program (SHP) for firefighters, which included some of the key components recommended for a comprehensive fatigue risk management program17: sleep health education, incorporating caffeine re-education, and advice on dealing with shiftwork, as well as screening for common undiagnosed sleep disorders. We educated and screened almost 7000 firefighters in 66 US fire departments across 32 states, with departments ranging in size from 22 to 1574 firefighters. Sleep disorders were highly prevalent in these active-duty career firefighters, with over one-third (37%) of firefighters screening positive for at least one sleep disorder, most of whom were previously undiagnosed. Twenty-eight percent screened positive for obstructive sleep apnea (OSA), 6% for insomnia, 9% for shift work disorder (SWD), and 3% for restless legs syndrome (RLS). Compared with those who did not screen positive, firefighters who screened positive for a sleep disorder were 3.5 times more likely to report getting injured, more than twice as likely to take a sick day or self-report falling asleep while driving, and had double the risk of reporting a motor vehicle crash.4 In the current study, we employed multiple approaches to evaluate the reach and effectiveness of three delivery methods for the SHP: expert-led (EL); train-the-trainer (TT); and online (OL). We characterized participation rates, knowledge gained by firefighters after completing the education, the rate of evaluation, and treatment for firefighters identified as being at risk for a sleep disorder, and the perceived strengths and challenges associated with each implementation methodology.

Background Because psychological approaches are likely to produce sustained benefits without the risk for tolerance or adverse effects associated with pharmacologic approaches, cognitive behavioral therapy for insomnia (CBT-i) is now commonly recommended as first-line treatment for chronic insomnia. Purpose To determine the efficacy of CBT-i on diary measures of overnight sleep in adults with chronic insomnia. Data sources Searches of MEDLINE, EMBASE, PsycINFO, CINAHL, the Cochrane Library, and PubMed Clinical Queries from inception to 31 March 2015, supplemented with manual screening. Study selection Randomized, controlled trials assessing the efficacy of face-to-face, multimodal CBT-i compared with inactive comparators on overnight sleep in adults with chronic insomnia. Studies of insomnia comorbid with medical, sleep, or psychiatric disorders were excluded. Data extraction Study characteristics, quality, and data were assessed independently by 2 reviewers. Main outcome measures were sleep onset latency (SOL), wake after sleep onset (WASO), total sleep time (TST), and sleep efficiency (SE%). Data synthesis Among 292 citations and 91 full-text articles reviewed, 20 studies (1162 participants [64% female; mean age, 56 years]) were included. Approaches to CBT-i incorporated at least 3 of the following: cognitive therapy, stimulus control, sleep restriction, sleep hygiene, and relaxation. At the posttreatment time point, SOL improved by 19.03 (95% CI, 14.12 to 23.93) minutes, WASO improved by 26.00 (CI, 15.48 to 36.52) minutes, TST improved by 7.61 (CI, -0.51 to 15.74) minutes, and SE% improved by 9.91% (CI, 8.09% to 11.73%). Changes seemed to be sustained at later time points. No adverse outcomes were reported. Limitation Narrow inclusion criteria limited applicability to patients with comorbid insomnia and other sleep problems, and accuracy of estimates at later time points was less clear. Conclusion CBT-i is an effective treatment for adults with chronic insomnia, with clinically meaningful effect sizes. Primary funding source None. (PROSPERO registration number: CRD42012002863).

In 2007, as part of the Massachusetts graduated driver-licensing program designed to allow junior operators (ages 16½-17 years) to gain experience before receiving full licensure, stringent penalties were introduced for violating a law prohibiting unsupervised driving at night; driver education, including drowsy driving education, became mandatory; and other new restrictions and penalties began. We evaluated the impact of these changes on police-reported vehicle crash records for one year before and five years after the law's implementation in drivers ages 16-17, inclusive, and two comparison groups. We found that crash rates for the youngest drivers fell 18.6 percent, from 16.24 to 13.22 per 100 licensed drivers. For drivers ages 18-19 the rates fell by 6.7 percent (from 9.59 to 8.95 per 100 drivers), and for those ages 20 and older, the rate remained relatively constant. The incidence rate ratio for drivers ages 16-17 relative to those ages 20 and older decreased 19.1 percent for all crashes, 39.8 percent for crashes causing a fatal or incapacitating injury, and 28.8 percent for night crashes. Other states should consider implementing strict penalties for violating graduated driver-licensing laws, including restrictions on unsupervised night driving, to reduce the risk of sleep-related crashes in young people.

Study objectives The absence of a screening questionnaire for delayed sleep phase disorder (DSPD) remains a barrier to its detection and subsequent clinical evaluation. We developed a questionnaire to screen for DSPD risk and assessed its impact on self-reported absenteeism and functioning in work/school, social, and family life. Design Cross-sectional, with 13,844 individuals responding to a survey through an Internet survey provider, from which 1315 completed surveys were obtained from eligible participants. Participants A total of 1315 individuals who self-identified as evening type (n = 979) or as non-evening type (n = 356). Measurements and results A total of 295 participants were at high risk for DSPD, which is 5.1% of the total eligible survey respondents and 22.4% of our final sample with completed surveys. Compared to those who were not at high risk for DSPD, those who were at high risk were more likely to report frequent absenteeism, frequent loss of productivity, disruption to work or school activities, disruption to social life or leisure activities, and disruption to family life or home responsibilities. Difficulty with daytime sleepiness was more common in those at high risk for DSPD than those who were not. Increased sleep deficit on nights before school or work was also associated with more frequent difficulties with daytime sleepiness; 15.4% of those with no sleep deficit reported always or usually having difficulties with daytime sleepiness compared to 55.7% of those with a sleep deficit of 3 hours or more. Conclusions DSPD risk is associated with increased absenteeism and impaired functioning in work/school, social, and family life.

OBJECTIVE: Sleep problems are commonly reported following alcohol and cannabis abuse, but our understanding of sleep in non-clinical drug using populations is limited. The present study examined the sleep characteristics of alcohol and cannabis users recruited from the wider community. METHODS: Two hundred forty-eight self-identified alcohol and/or cannabis users (131 women and 117 men) with a mean age of 26.41 years completed an online study that was advertised via online forums, print media and flyers. As part of the study, participants completed validated sleep scales assessing sleep quality (Pittsburgh Sleep Quality Index) and excessive daytime sleepiness (Epworth Sleepiness Scale) in addition to validated drug scales assessing alcohol (Alcohol Use Disorders Identification Test) and cannabis (Marijuana Screening Inventory) use. RESULTS: Problems with sleep quality were more commonly reported than were complaints of excessive daytime sleepiness. Clinically significant poor sleep quality was associated with comorbid problem alcohol and cannabis use. Women reporting problem alcohol and cannabis use had poorer sleep outcomes than men. CONCLUSIONS: Social drug users who report risky alcohol and cannabis use also report poor sleep. Poor sleep quality likely exacerbates any drug-associated problems in non-clinical populations. Copyright © 2015 John Wiley & Sons, Ltd. Language: en

UNLABELLED Insomnia and depression are highly comorbid conditions that show a complex, bidirectional relationship. This study examined whether cognitive-behavioral therapy for insomnia (CBT-I) delivered by a therapist compared with self-help CBT-I (written materials only) reduces insomnia and depression severity in individuals with comorbid insomnia and depression. A total of 41 participants (18-64 years; 25 females) with comorbid depression and insomnia, treated with antidepressants for at least 6 weeks, were randomized to receive 4 sessions of either CBT-I or self-help CBT-I over 8 weeks. Insomnia (Insomnia Severity Index [ISI]) and depression (Beck Depression Inventory-II [BDI-II]) were assessed at baseline, following each session, and at 3-month follow-up. Secondary outcomes were sleep quality and duration (actigraphy and diaries), anxiety, fatigue, and daytime sleepiness. Compared with self-help CBT-I, BDI-II scores in the CBT-I group dropped by 11.93 (95% confidence interval [CI] [6.60, 17.27], p < .001) more points, and ISI scores dropped by 6.59 (95% CI [3.04, 10.15], p = .001) more points across treatment. At 3-month follow-up, 61.1% of CBT-I participants were in clinical remission from their insomnia and depression, compared with 5.6% of the self-help group. CONCLUSIONS CBT-I administered by a therapist produced significant reductions in both insomnia and depression severity posttreatment and at follow-up, compared with a control condition in which participants received only written CBT-I material. Targeting insomnia through CBT-I is efficacious for treating comorbid insomnia and depression, and should be considered an important adjunct therapy for patients with depression whose symptoms have not remitted through antidepressant treatment.

Study Objectives: Heart attacks and motor vehicle crashes are the leading causes of death in US fi refi ghters. Given that sleep disorders are an independent risk factor for both of these, we examined the prevalence of common sleep disorders in a national sample of fi refi ghters and their association with adverse health and safety outcomes. Methods: Firefi ghters (n = 6,933) from 66 US fi re departments were assessed for common sleep disorders using validated screening tools, as available. Firefi ghters were also surveyed about health and safety, and documentation was collected for reported motor vehicle crashes. Results: A t otal o f 3 7.2% o f fi refi ghters s creened p ositive for any sleep disorder including obstructive sleep apnea (OSA), 28.4%; insomnia, 6.0%; shift work disorder, 9.1%; and restless legs syndrome, 3.4%. Compared with those who did not screen positive, fi refi ghters who screened positive for a sleep disorder were more likely to report a motor vehicle crash (adjusted odds ratio 2.00, 95% CI 1.29-3.12, p = 0.0021) and were more likely to self-report falling asleep while driving (2.41, 2.06-2.82, p < 0.0001). Firefi ghters who screened positive for a sleep disorder were more likely to report having cardiovascular disease (2.37, 1.54-3.66, p < 0.0001), diabetes ( 1.91, 1 .31-2.81, p = 0 .0009), d epression ( 3.10, 2.49-3.85, p < 0.0001), and anxiety (3.81, 2.87-5.05, p < 0.0001), and to report poorer health status (p < 0.0001) than those who did not screen positive. Adverse health and safety associations persisted when OSA and non-OSA sleep disorders were examined separately. Conclusions: Sleep disorders are prevalent in fi refi ghters and are associated with increased risk of adverse health and safety outcomes. Future research is needed to assess the effi cacy of occupational sleep disorders prevention, screening, and treatment programs in fi re departments to reduce these safety and health risks.

Drowsiness is a major risk factor for motor vehicle and occupational accidents. Real-time objective indicators of drowsiness could potentially identify drowsy individuals with the goal of intervening before an accident occurs. Several ocular measures are promising objective indicators of drowsiness; however, there is a lack of studies evaluating their accuracy for detecting behavioral impairment due to drowsiness in real time.In this study, eye movement parameters were measured during vigilance tasks following restricted sleep and in a rested state (n = 33 participants) at three testing points (n = 71 data points) to compare ocular measures to a gold standard measure of drowsiness (OSLER). The utility of these parameters for detecting drowsiness-related errors was evaluated using receiver operating characteristic curves (ROC) (adjusted by clustering for participant) and identification of optimal cutoff levels for identifying frequent drowsiness-related errors (4 missed signals in a minute using OSLER). Their accuracy was tested for detecting increasing frequencies of behavioral lapses on a different task (psychomotor vigilance task [PVT]).Ocular variables which measured the average duration of eyelid closure (inter-event duration [IED]) and the ratio of the amplitude to velocity of eyelid closure were reliable indicators of frequent errors (area under the curve for ROC of 0.73 to 0.83, p0.05). IED produced a sensitivity and specificity of 71% and 88% for detecting ≥ 3 lapses (PVT) in a minute and 100% and 86% for ≥ 5 lapses. A composite measure of several eye movement characteristics (Johns Drowsiness Scale) provided sensitivities of 77% and 100% for detecting 3 and ≥ 5 lapses in a minute, with specificities of 85% and 83%, respectively.Ocular measures, particularly those measuring the average duration of episodes of eye closure are promising real-time indicators of drowsiness.

The current study characterized the temporal dynamics of ocular indicators of sleepiness during extended sleep restriction. Ten male participants (mean age ± SD = 23.3 ± 1.6 years) underwent 40 h of continuous wakefulness under constant routine (CR) conditions; they completed the Karolinska Sleepiness Scale (KSS) and a 10-min auditory psychomotor vigilance task (aPVT) hourly. Waking electroencephalography (EEG) and ocular measures were recorded continuously throughout the CR. Infrared-reflectance oculography was used to collect the ocular measures positive and negative amplitude-velocity ratio, mean blink duration, the percentage of eye closure, and a composite score of sleepiness levels (Johns Drowsiness Scale). All ocular measures, except blink duration, displayed homeostatic and circadian properties. Only circadian effects were detected in blink duration. Significant, phase-locked cross-correlations (p < 0.05) were detected between ocular measures and aPVT reaction time (RT), aPVT lapses, KSS, and EEG delta-theta (0.5-5.5 Hz), theta-alpha (5.0-9.0 Hz), and beta (13.0-20.0 Hz) activity. Receiver operating characteristic curve analysis demonstrated reasonable sensitivity and specificity of ocular measures in correctly classifying aPVT lapses above individual baseline thresholds (initial 16 h of wakefulness). Under conditions of sleep restriction, ocular indicators of sleepiness paralleled performance impairment and self-rated sleepiness levels, and demonstrated their potential to detect sleepiness-related attentional lapses. These findings, if reproduced in a larger sample, will have implications for the use of ocular-based sleepiness-warning systems in operational settings. © 2013 The Author(s).

Sleep disturbance is common in autism spectrum disorder (ASD), but longitudinal trajectories are poorly defined. This study measured sleep disturbance at baseline and 1 year later examining change over time and associated problem behaviors. Participants were 84 gender-matched children, aged between 7 and 12 years at baseline; 46 children were diagnosed with ASD, and 38 were typically developing (TYP) children. Parent reports on a range of scales were collected. The ASD group had more sleep disturbance than the TYP group. Sleep disturbance decreased over the year in children with ASD, but not in TYP children. Reduced sleep disturbance was associated with improved social ability. Sleep disturbance at baseline predicted later anxiety. Findings indicated different trajectories of sleep disturbance in ASD, and the implications are discussed.

Background. Fatigue is a common, persistent complaint following traumatic brain injury (TBI). Effective treatment is not well established. Objective. The current study aimed to investigate the efficacy of 4 weeks of light therapy for fatigue in patients with TBI. Methods. We undertook a randomized, placebo-controlled study of 4-week, 45 min/morning, home-based treatment with short wavelength (blue) light therapy (λmax = 465 nm, 84.8 µW/cm2, 39.5 lux, 1.74 × 1014 photons/cm2/s) compared with yellow light therapy (λmax = 574 nm, 18.5 µW/cm2, 68 lux, 1.21 × 1012 photons/cm2/s) containing less photons in the short wavelength range and a no treatment control group (n = 10 per group) in patients with TBI who self-reported fatigue and/or sleep disturbance. Assessments of fatigue and secondary outcomes (self-reported daytime sleepiness, depression, sleep quality, and sustained attention) were conducted over 10 weeks at baseline (week −2), midway through and at the end of light therapy (weeks 2 and 4), and 4 weeks following cessation of light therapy (week 8). Results. After controlling age, gender, and baseline depression, treatment with high-intensity blue light therapy resulted in reduced fatigue and daytime sleepiness during the treatment phase, with evidence of a trend toward baseline levels 4 weeks after treatment cessation. These changes were not observed with lower-intensity yellow light therapy or no treatment control conditions. There was also no significant treatment effect observed for self-reported depression or psychomotor vigilance performance. Conclusions. Blue light therapy appears to be effective in alleviating fatigue and daytime sleepiness following TBI and may offer a noninvasive, safe, and nonpharmacological alternative to current treatments.

a b s t r a c t Background: Ecstasy users report a number of adverse effects following use including mood and sleep disturbances. The present study examined differences in characteristics of ecstasy use (amount, frequency of use, reported harm resulting from use) between males and females and assessed relationships between ecstasy use, sleep quality and mental health outcomes. Methods: An online survey of 268 ecstasy users (54.1% male, 45.9% female) was conducted. Validated sleep instruments assessing sleep quality and excessive daytime sleepiness, as well as questionnaires regarding physical and mental health (measured using the short-form health survey 12 (SF-12) and details of drug use were included. Results: Male ecstasy users reported taking larger amounts of ecstasy, but were not more frequent users compared to females. Female ecstasy users were more likely to report increased harm following ecstasy including: feelings of guilt and remorse; failing to do what was normally expected of them; and having been told by others to cut down their ecstasy use. There were interactions between amount and gender and frequency and gender in predicting use of sleep medication and daytime dysfunction. There was a positive correlation between poorer sleep quality and negative mood, although this relationship was not moderated by sex. Conclusions: There is a significant association between sleep quality and mood disturbance in ecstasy users suggesting that these negative outcomes are co-morbid. These findings have implications for the treatment and advice given to ecstasy users who are experiencing sleep and/or mood related complaints.

Currently, the National Transport Commission is considering four options to form the regulatory framework for rail safety within Australia with respect to fatigue. While the National Transport Commission currently recommends no limitations around hours of work or rest, we provide evidence which suggests regulatory frameworks should incorporate a traditional hours of service regulation over more flexible policies. Our review highlights: Shift durations >12 h are associated with a doubling of risk for accident and injury. Fatigue builds cumulatively with each successive shift where rest in between is inadequate (

BACKGROUND: . Sleep changes are frequently reported following traumatic brain injury (TBI) and have an impact on rehabilitation and quality of life following injury. Potential causes include injury to brain regions associated with sleep regulation, as well as secondary factors, including depression, anxiety, and pain. Understanding the nature and causes of sleep changes following TBI represents a vital step in developing effective treatments. OBJECTIVE: . The study aimed to investigate subjective sleep changes in a community-based sample of individuals with TBI in comparison with noninjured age- and sex-matched controls and to explore the impact of secondary factors (pain, anxiety, depression, employment) on these self-reported sleep changes. METHODS: : A total of 153 participants with mild to severe TBI and 128 noninjured controls completed self-report measures relating to their sleep quality, daytime sleepiness, mood, fatigue, and pain and completed a sleep diary each day for 7 days. RESULTS: . Compared with the noninjured controls, participants with TBI reported significantly poorer sleep quality and higher levels of daytime sleepiness; sleep diaries revealed longer sleep onset latency, poorer sleep efficiency, longer sleep duration, and more frequent daytime napping in the TBI group, as well as earlier bedtimes and greater total sleep duration. Anxiety, depression, and pain were associated with poorer sleep quality. Greater injury severity was also associated with a need for longer sleep time. CONCLUSION: . These findings highlight the importance of assessing and addressing pain, anxiety, and depression as part of the process of treating TBI-related sleep disturbances. Language: en

Study objective At least 15% of the full-time work force is shift workers. Working during the overnight hours, early morning start times, and variable or rotating schedules present a challenge to the circadian system, and these shifts are associated with adverse health and safety consequences. Shift work disorder (SWD), a primary (circadian rhythm) sleep disorder indicated by excessive daytime sleepiness and/or insomnia associated with a shiftwork schedule, is under-recognized by primary care physicians. We sought to develop and validate a questionnaire to screen for high risk of SWD in a shift working population. Design Shift workers completed a 26-item questionnaire and were evaluated by a sleep specialist (physician) who diagnosed them as either positive or negative for SWD. The physician assessment of SWD was guided by a flow chart that operationalized the ICSD-2 criteria for SWD. Setting 18 sleep clinics in the USA. Patients or participants 311 shift workers. Interventions Not applicable. Measurements and results Responses to the items in the questionnaire were entered into a series of discrimination function analyses to determine the diagnostic value of the items and the fewest number of questions with the best predictive value. The function was then cross-validated. A final 4-item questionnaire has 89% positive predictive value and 62% negative predictive value (sensitivity = 0.74; specificity = 0.82). Conclusions This Shiftwork Disorder Screening Questionnaire may be appropriate for use in primary care settings to aid in the diagnosis of SWD.

Brain networks subserving alertness in humans interact with those for spatial attention orienting. We employed blue-enriched light to directly manipulate alertness in healthy volunteers. We show for the first time that prior exposure to higher, relative to lower, intensities of blue-enriched light speeds response times to left, but not right, hemifield visual stimuli, via an asymmetric effect on right-hemisphere parieto-occipital α-power. Our data give rise to the tantalising possibility of light-based interventions for right hemisphere disorders of spatial attention.

Objective This study aimed to investigate sleep and circadian phase in the relationships between neurobehavioral performance and the number of consecutive shifts worked. Methods Thirty-four shift workers [20 men, mean age 31.8 (SD 10.9) years] worked 2�7 consecutive night shifts immediately prior to a laboratory-based, simulated night shift. For 7 days prior, participants worked their usual shift sequence, and sleep was assessed with logs and actigraphy. Participants completed a 10-minute auditory psychomotor vigilance task (PVT) at the start (~21:00 hours) and end (~07:00 hours) of the simulated night shift. Mean reaction times (RT), number of lapses and RT distribution was compared between those who worked 2�3 consecutive night shifts versus those who worked 4�7 shifts. Results Following 4�7 shifts, night shift workers had significantly longer mean RT at the start and end of shift, compared to those who worked 2�3 shifts. The slowest and fastest 10% RT were significantly slower at the start, but not end, of shift among participants who worked 4�7 nights. Those working 4�7 nights also demonstrated a broader RT distribution at the start and end of shift and had significantly slower RT based on cumulative distribution analysis (5th, 25th, 50th, 75th percentiles at the start of shift; 75th percentile at the end of shift). No group differences in sleep parameters were found for 7 days and 24 hours prior to the simulated night shift. Conclusion A greater number of consecutive night shifts has a negative impact on neurobehavioral performance, likely due to cognitive slowing. © 2016, Nordic Association of Occupational Safety and Health. All rights reserved.

To assess the relationships between sleepiness and the incidence of adverse driving events in nurses commuting to and from night and rotating shifts, 27 rotating and permanent night shift-working nurses were asked to complete daily sleep and duty logs, and wear wrist-activity monitors for 2 weeks (369 driving sessions). During all commutes, ocular measures of drowsiness, including the Johns Drowsiness Scale score, were assessed using the Optalert™ system. Participants self-reported their subjective sleepiness at the beginning and end of each drive, and any events that occurred during the drive. Rotating shift nurses reported higher levels of sleepiness compared with permanent night shift nurses. In both shift-working groups, self-reported sleepiness, drowsiness and drive events were significantly higher during commutes following night shifts compared with commutes before night shifts. Strong associations were found between objective drowsiness and increased odds of driving events during commutes following night shifts. Maximum total blink duration (mean = 7.96 s) during the drive and pre-drive Karolinska Sleepiness Scale (mean = 5.0) were associated with greater incidence of sleep-related events [OR, 5.35 (95% CI, 1.32, 21.60), OR, 1.69 (95% CI, 1.04, 2.73), respectively]. Inattention was strongly associated with a Johns Drowsiness Scale score equal to or above 4.5 [OR, 4.58 (95% CI, 1.26-16.69)]. Hazardous driving events were more likely to occur when drivers had been awake for 16 h or more [OR, 4.50 (95% CI, 1.81, 11.16)]. Under real-world driving conditions, shift-working nurses experience high levels of drowsiness as indicated by ocular measures, which are associated with impaired driving performance following night shift work. Keywords: Driver distraction; Language: en

MDMA (ecstasy) is an illicit drug which has pharmacological actions on the serotonin system, leading to a number of physiological and behavioral changes. Research conducted in both animals and humans has focused on how ecstasy use affects systems or functions in which serotonin has a regulatory role including mood, sleep and circadian rhythms. In this paper we review the evidence with respect to changes in sleep and circadian rhythms following ecstasy use. Studies of the subjective measurement of sleep have suggested that there are changes in sleep quality and duration following ecstasy use, while research utilizing objective measures including polysomnog-raphy has highlighted changes in sleep architecture following ecstasy use. Collectively these findings suggest that there are consequences associated with ecstasy use, and the implications of these findings for ecstasy users will be examined. Finally, preliminary evidence from the animal literature implicating ecstasy as having specific effects on the circadian system will be reviewed. A discussion of the limitations of the current evidence for such a claim is presented, and possible directions for future research are explored.

Traveling on a long-haul flight, tending to family emergencies or caregiver responsibilities, and rotating shift work schedules are all examples of situations in which the habitual nocturnal sleep episode may be disrupted while an individual may still be required to subsequently remain awake and alert. When possible, a planned nap can minimize the detrimental impact of the impending bout of sustained wakefulness on alertness and performance.1 It may be difficult, however, to achieve sleep outside of the habitual sleep period, particularly during the afternoon and early evening when the circadian system promotes wakefulness.2 Theoretically, a hypnotic medication that does not impair neurobehavioral performance could be an effective strategy to assist with planned naps and improve waking functioning. Ramelteon is a selective MT1/MT2 melatonin receptor agonist3 approved by the Food and Drug Administration for the treatment of insomnia. Preclinical animal studies of ramelteon in rats, cats, and mice demonstrated that doses up to 30 mg/kg did not impair subsequent performance on tasks of learning, memory, and motor control.4–6 In phase-advance models of transient insomnia in humans and in patients with chronic insomnia, ramelteon has been reported to lack significant adverse neurobehavioral effects on performance on measures such as the digit symbol substitution task (DSST) and delayed recall.7–11 Although these studies generally assessed the effect of ramelteon on next-day neurobehavioral performance following an 8-h nocturnal sleep period, two studies showed that ramelteon at doses of 4-160 mg did not impair measures such as DSST, word recall, balance, or hand-eye coordination during the waking day after morning administration.3,12 Additionally, in a recent crossover study in which elderly participants aged 65 or older received ramelteon, zolpidem, or placebo 30 min prior to sleep and were awakened 2 h after dosing, ramelteon did not impair middle-of-the-night balance or memory, whereas zolpidem impaired these measures.13 Therefore, given its apparent neurobehavioral safety profile when tested under a variety of circumstances, we hypothesized that ramelteon could improve sleep efficiency outside of the habitual sleep episode and subsequently improve waking performance. BRIEF SUMMARY Current Knowledge/Study Rationale: A nap is often recommended before working a night shift to improve alertness and performance, but naps in the evening may be difficult to achieve secondary to circadian alerting mechanisms. Modulation of the melatonin receptor system can improve sleep in the early evening, perhaps by attenuating circadian arousal mechanisms, and may potentially improve performance during the following night shift. Study Impact: While prior studies suggested that ramelteon lacks cognitive side effects, we demonstrate neurobehavioral impairments for up to 12 hours after administration. We caution that conditions of high homeostatic sleep pressure coinciding with the circadian performance nadir during a night shift may increase the sensitivity for residual hypnotic-induced deficits on subsequent waking performance. We used a simulated night-shift model to mimic a real-world situation in which individuals may use a hypnotic prior to a nap with the goal of improving nap sleep efficiency and enhancing subsequent alertness and performance. This proof-of-concept study was conducted using a randomized, double-blind, placebo controlled, crossover inpatient study design.

Primary insomnia is a sleep disorder where the subjective complaint of initiating or maintaining sleep, or the experience of sleep that is non-refreshing, cannot be directly attributed to a comorbid medical or psychiatric disorder. For a diagnosis of primary insomnia, a patient must also report that the nighttime sleep disturbance is impacting upon daytime functioning. Yet, while subjective complaints of impaired wake-time functioning are well documented, consistent objective evidence of these impairments has proved elusive, particularly with regard to cognitive functioning. We aimed to review the body of literature examining neurobehavioural impairments in primary insomnia to identify which cognitive domains appear to be most consistently impaired in this group. The relatively few studies that have investigated neurobehavioural performance deficits in patients with primary insomnia have produced inconsistent and sometimes conflicting findings. It is suggested that methodological limitations, including heterogeneous test populations, variable testing protocols and conditions as well as unsuitable cognitive tasks have contributed to our inability to describe unequivocally the daytime impairments associated with insomnia. Based on our review, it appears that the deficits associated with insomnia are relatively subtle and may be qualitatively different to those that result from other sleep disorders and from imposed sleep deprivation. Attention tasks, which have a high cognitive load, and working memory tasks appear to show performance deficits more often than not in insomnia patients. It is important to more definitively characterise the daytime impairments associated with primary insomnia so that the efficacy of treatments to remedy the wake-time consequences of the disorder, in addition to the nighttime symptoms, can be investigated.

Over the past 25 years, there has been substantial growth in the field of melatonin and melatonin analogues. Following the first demonstration that exogenous melatonin can entrain the mammalian circadian system and the discovery of the phase-shifting and sleep-promoting properties of the hormone in humans, several groups have demonstrated the potential for melatonin to be used as a treatment for circadian rhythm sleep disorders (CRSDs). Clinical development of melatonin agonists for sleep and psychiatric disorders has also provided significant momentum to this field. There is increasing interest in the use of melatonin-like compounds in the treatment of primary insomnia; however, the mechanisms underlying these effects remain unclear. Herein we review the role of melatonin and melatonin receptors in the circadian regulation of sleep, the phase-shifting and sleep-promoting properties of exogenous melatonin, and some of the melatonin agonists that have been developed or are under development for the treatment of primary insomnia, CRSDs, and major depression.

Summary Background Circadian rhythm sleep disorders are common causes of insomnia for millions of individuals. We did a phase II study to establish efficacy and physiological mechanism, and a phase III study to confirm efficacy of the melatonin agonist tasimelteon (VEC-162) for treatment of transient insomnia associated with shifted sleep and wake time. Methods We undertook phase II and phase III randomised, double-blind, placebo-controlled, parallel-group studies. In a phase II study, 39 healthy individuals from two US sites were randomly assigned to tasimelteon (10 [n=9], 20 [n=8], 50 [n=7], or 100 mg [n=7]) or placebo (n=8). We monitored individuals for 7 nights: 3 at baseline, 3 after a 5-h advance of sleep–wake schedule with treatment before sleep, and 1 after treatment; we measured plasma melatonin concentration for circadian phase assessment. In a phase III study, 411 healthy individuals from 19 US sites, who had transient insomnia induced in a sleep clinic by a 5-h advance of the sleep–wake schedule and a first-night effect in a sleep clinic, were given tasimelteon (20 [n=100], 50 [n=102], or 100 mg [n=106]) or placebo (n=103) 30 min before bedtime. Prespecified primary efficacy outcomes were polysomnographic sleep efficiency (phase II study), latency to persistent sleep (phase III study), and circadian phase shifting (phase II study). Analysis was by intention to treat. Safety was assessed in both studies. These trials are registered with ClinicalTrials.gov, numbers NCT00490945 and NCT00291187. Findings In the phase II study, tasimelteon reduced sleep latency and increased sleep efficiency compared with placebo. The shift in plasma melatonin rhythm to an earlier hour was dose dependent. In the phase III study, tasimelteon improved sleep latency, sleep efficiency, and wake after sleep onset (ie, sleep maintenance). The frequency of adverse events was similar between tasimelteon and placebo. Interpretation After an abrupt advance in sleep time, tasimelteon improved sleep initiation and maintenance concurrently with a shift in endogenous circadian rhythms. Tasimelteon may have therapeutic potential for transient insomnia in circadian rhythm sleep disorders. Funding Vanda Pharmaceuticals Inc.

This special issue of Chronobiology International presents a selection of papers originally delivered at the 18th International Symposium on Shift Work and Working Time, held at Yeppoon, Australia, in August 2007. The key theme of the symposium was "Aging and Working Time: Creating Safe Environments." Older workers are widely believed to experience greater difficulty than younger workers adapting to shift work and irregular work schedules. However, while the three reviews of age effects published here (Costa & Di Milia, 2008; Folkard, 2008b; Gander & Signal, 2008) identify evidence that older workers do indeed adapt less well, they also demonstrate that much more research is urgently required. The remaining papers address various aspects of the impact of work schedules on health, safety, sleep, and performance. They can be divided into three broad categories: circadian and other periodic factors; sleep, sleepiness, and fatigue; and other aspects of health and adjustment. This collection of papers showcases the best of contemporary research on the safety and health effects of working hours, continuing the tradition established by the two previous issues of the journal devoted to earlier symposia on shift work and working time.

Summary Heart rate (HR) and heart rate variability (HRV) undergo marked fluctuations over the 24-h day. Although controversial, this 24-h rhythm is thought to be driven by the sleep–wake/rest–activity cycle as well as by endogenous circadian rhythmicity. We quantified the endogenous circadian rhythm of HR and HRV and investigated whether this rhythm can be shifted by repeated melatonin administration while exposed to an altered photoperiod. Eight healthy males (age 24.4 ± 4.4 years) participated in a double-blind cross-over design study. In both conditions, volunteers were scheduled to 16 h–8 h rest : wake and dark : light cycles for nine consecutive days preceded and followed by 29-h constant routines (CR) for assessment of endogenous circadian rhythmicity. Melatonin (1.5 mg) or placebo was administered at the beginning of the extended sleep opportunities. For all polysomnographically verified wakefulness periods of the CR, we calculated the high- (HF) and low- (LF) frequency bands of the power spectrum of the R–R interval, the standard deviation of the normal-to-normal (NN) intervals (SDNN) and the square root of the mean-squared difference of successive NN intervals (rMSSD). HR and HRV variables revealed robust endogenous circadian rhythms with fitted maxima, respectively, in the afternoon (16:36 hours) and in the early morning (between 05:00 and 06:59 hours). Melatonin treatment phase-advanced HR, HF, SDNN and rMSSD, and these shifts were significantly greater than after placebo treatment. We conclude that endogenous circadian rhythmicity influences autonomic control of HR and that the timing of these endogenous rhythms can be altered by extended sleep/rest episodes and associated changes in photoperiod as well as by melatonin treatment.

Cognitive behavioral therapy for insomnia (CBT-I) has been shown to improve both sleep and depressive symptoms, but predictors of depression outcome following CBT-I have not been well examined. This study investigated how chronotype (i.e., morningness-eveningness trait) and changes in sleep efficiency (SE) were related to changes in depressive symptoms among recipients of CBT-I.Included were 419 adult insomnia outpatients from a sleep disorders clinic (43.20% males, age mean ± standard deviation = 48.14 ± 14.02). All participants completed the Composite Scale of Morningness and attended at least 4 sessions of a 6-session group CBT-I. SE was extracted from sleep diary; depressive symptoms were assessed using the Beck Depression Inventory (BDI) prior to (Baseline), and at the end (End) of intervention.Multilevel structural equation modeling revealed that from Baseline to End, SE increased and BDI decreased significantly. Controlling for age, sex, BDI, and SE at Baseline, stronger evening chronotype and less improvement in SE significantly and uniquely predicted less reduction in BDI from Baseline to End. Chronotype did not predict improvement in SE.In an insomnia outpatient sample, SE and depressive symptoms improved significantly after a CBT-I group intervention. All chronotypes benefited from sleep improvement, but those with greater eveningness and/or less sleep improvement experienced less reduction in depressive symptom severity. This suggests that evening preference and insomnia symptoms may have distinct relationships with mood, raising the possibility that the effect of CBT-I on depressive symptoms could be enhanced by assessing and addressing circadian factors.

Although sleep restriction is associated with decrements in daytime alertness and neurobehavioural performance, there are considerable inter-individual differences in the degree of impairment. This study examined the effects of short-term sleep restriction on neurobehavioural performance and sleepiness, and the associations between individual differences in impairments and circadian rhythm phase. Healthy adults (n = 43; 22 M) aged 22.5 ± 3.1 (mean ± SD) years maintained a regular 8:16 h sleep:wake routine for at least three weeks prior to laboratory admission. Sleep opportunity was restricted to 5 hours time-in-bed at home the night before admission and 3 hours time-in-bed in the laboratory, aligned by wake time. Hourly saliva samples were collected from 5.5 h before until 5 h after the pre-laboratory scheduled bedtime to assess dim light melatonin onset (DLMO) as a marker of circadian phase. Participants completed a 10-min auditory Psychomotor Vigilance Task (PVT), the Karolinska Sleepiness Scale (KSS) and had slow eye movements (SEM) measured by electrooculography two hours after waking. We observed substantial inter-individual variability in neurobehavioural performance, particularly in the number of PVT lapses. Increased PVT lapses (r = -0.468, p < 0.01), greater sleepiness (r = 0.510, p < 0.0001), and more slow eye movements (r = 0.375, p = 0.022) were significantly associated with later DLMO, consistent with participants waking at an earlier circadian phase. When the difference between DLMO and sleep onset was less than 2 hours, individuals were significantly more likely to have at least three attentional lapses the following morning. This study demonstrates that the phase of an individual’s circadian system is an important variable in predicting the degree of neurobehavioural performance impairment in the hours after waking following sleep restriction, and confirms that other factors influencing performance decrements require further investigation.

Fatigue is recognised as one of the most important safety issues in transportation. The current paper identifies and compares the laws and regulations of four English speaking nations that limit working hours for safety purposes, and evaluates them against eight fatigue-related criteria. In addition, International and European Union law are considered where relevant. Two different styles of regulation were utilized by the countries surveyed: a prescriptive “Hours of Service” approach, and a non-prescriptive “outcomes” approach. The advantages and disadvantages of these two models are discussed. None of the rules were assessed as addressing all eight criteria. A proposal for a hybrid approach between the prescriptive and non-prescriptive systems is presented.

The rhythm of plasma melatonin originating from the pineal gland and driven by the circadian pacemaker located in the suprachiasmatic nucleus is closely associated with the circadian (approximately 24 h) variation in sleep propensity and sleep spindle activity in humans. We investigated the contribution of melatonin to variation in sleep propensity, structure, duration and EEG activity in a protocol in which sleep was scheduled to begin during the biological day, i.e. when endogenous melatonin concentrations are low. The two 14 day trials were conducted in an environmental scheduling facility. Each trial included two circadian phase assessments, baseline sleep and nine 16 h sleep opportunities (16.00–08.00 h) in near darkness. Eight healthy male volunteers (24.4 ± 4.4 years) without sleep complaints were recruited, and melatonin (1.5 mg) or placebo was administered at the start of the first eight 16 h sleep opportunities. During melatonin treatment, sleep in the first 8 h of the 16 h sleep opportunities was increased by 2 h. Sleep per 16 h was not significantly different and approached asymptotic values of 8.7 h in both conditions. The percentage of rapid eye movement (REM) sleep was not affected by melatonin, but the percentage of stage 2 sleep and sleep spindle activity increased, and the percentage of stage 3 sleep decreased. During the washout night, the melatonin-induced advance in sleep timing persisted, but was smaller than on the preceding treatment night and was consistent with the advance in the endogenous melatonin rhythm. These data demonstrate robust, direct sleep-facilitating and circadian effects of melatonin without concomitant changes in sleep duration, and support the use of melatonin in the treatment of sleep disorders in which the circadian melatonin rhythm is delayed relative to desired sleep time.

Study Objectives: The study examined the relationship between the circadian rhythm of 6-sulphatoxymelatonin (aMT6s) and ocular measures of sleepiness and neurobehavioral performance in shift workers undergoing a simulated night shift. Methods: Twenty-two shift workers (mean age 33.4, SD 11.8 years) were tested at approximately the beginning (20:00) and the end (05:55) of a simulated night shift in the laboratory. At the time point corresponding to the end of the simulated shift, 14 participants were classifi ed as being within range of 6-sulphatoxymelatonin (aMT6s) acrophase\- defi ned as 3 hours before or after aMT6s peak\-and 8 were classifi ed as outside aMT6s acrophase range. Participants completed the Karolinska Sleepiness Scale (KSS) and the auditory psychomotor vigilance task (aPVT). Waking electroencephalography (EEG) was recorded and infrared refl ectance oculography was used to collect ocular measures of sleepiness: positive and negative amplitude/velocity ratio (PosAVR, NegAVR), mean blink total duration (BTD), the percentage of eye closure (%TEC), and a composite score of sleepiness levels (Johns Drowsiness Scale; JDS). Results: Participants who were tested within aMT6s acrophase range displayed higher levels of sleepiness on ocular measures (%TEC, BTD, PosAVR, JDS), objective sleepiness (EEG delta power frequency band), subjective ratings of sleepiness, and neurobehavioral performance, compared to those who were outside aMT6s acrophase range. Conclusions: The study demonstrated that objective ocular measures of sleepiness are sensitive to circadian rhythm misalignment in shift workers.

Fatigue is one of the most frequent sequelae of traumatic brain injury (TBI), although its causes are poorly understood. This study investigated the interrelationships between fatigue and sleepiness, vigilance performance, depression, and anxiety, using a structural equation modeling approach.Seventy-two participants with moderate to severe TBI (78% males) were recruited a median of 305 days postinjury. They completed the Fatigue Severity Scale, a vigilance task, the Epworth Sleepiness Scale, and Hospital Anxiety and Depression Scale. A model of the interrelationships between the study variables was developed, tested, and modified with path analysis.The modified model had a good overall fit (χ2 = 1.3, P = .54; comparative fit index = 1.0; root-mean square error of approximation = 0.0; standardized root-mean square residual = 0.02). Most paths in this model were significant (P.05). Fatigue predicted anxiety, depression, and daytime sleepiness. Depression predicted daytime sleepiness and poor vigilance, whereas anxiety tended to predict reduced daytime sleepiness.This model confirms the complexity of fatigue experience. It supports the hypothesis that fatigue after TBI is a cause, not a consequence, of anxiety, depression, and daytime sleepiness, which, in turn (especially depression), may exacerbate fatigue by affecting cognitive functioning. These findings suggest that to alleviate fatigue, it is important to address each of these factors. However, the findings need to be confirmed with a longitudinal research design.

Summary With increasing economic and social demands, we are rapidly evolving into a 24-h society. In any urban economy, about 20% of the population are required to work outside the regular 0800–1700 h working day and this figure is likely to increase. Although the increase in shiftwork has led to greater flexibility in work schedules, the ability to provide goods and services throughout the day and night, and possibly greater employment opportunities, the negative effects of shiftwork and chronic sleep loss on health and productivity are now being appreciated. For example, sleepiness surpasses alcohol and drugs as the greatest identifiable and preventable cause of accidents in all modes of transport. Industrial accidents associated with night work are common, perhaps the most famous being Chernobyl, Three Mile Island, and Bhopal

The common law position in Australia in relation to self‐induced intoxication and criminal responsibility is that evidence of intoxication should be taken into account when determining whether the Crown has proved beyond reasonable doubt that an accused person acted voluntarily and intentionally. In the Code jurisdictions, similar principles apply, although evidence of intoxication is generally only relevant to certain classes of offences. Although many legal commentaries on the issue of intoxication and criminal responsibility have been published in recent years, many of these have largely ignored the vast and rapidly growing scientific literature on the nature and effects of intoxication. This article describes the major effects of various psychoactive drugs, with particular emphasis on the potential effects of these drugs on criminal behaviour. The drugs are classified according to their major pharmacological properties — central nervous system depressants, central nervous system stimulants, opiates, c...

A recent focus of chronobiological studies has been to establish diurnal models as alternatives to the more frequently used nocturnal rodents. In the present study, light-dark (LD) entrainment characteristics were examined in one diurnal species, the Indian palm squirrel (Funambulus pennanti). Palm squirrels showed strongly diurnal locomotor activity rhythms (˜ 88 percent) under light-dark (LD) cycles, with activity bimodally distributed during the L phase. In comparison to a dim LD cycle, exposure to a bright LD cycle caused a phase advance in the onset of activity, an increase in daily activity levels and an increase in the duration of activity. Percentage diurnality, however, did not vary between bright and dim LD cycles. Activity rhythms reentrained in significantly fewer days after an 8 hour phase delay of the LD cycle compared to an 8 hour phase advance. In both cases, the direction of reentrainment followed the direction of the LD shift. When exposed to single light pulses (1 hour) presented at the...

SummaryThe pineal hormone melatonin is able to shift the timing of circadian rhythms, including the sleep–wake cycle, and to promote sleep. Melatonin agonists with similar properties have therapeutic potential for the treatment of circadian rhythm sleep disorders. Depression is specifically targeted by agomelatine, which is also a serotonin-2C (5-HT2C) antagonist.

Exogenous melatonin induces phase shifts in circadian rhythms ac cording to a phase response curve in nocturnal rodents, several nonmammalian diurnal species, and humans. Daily administration of melatonin entrains rhythms within a narrow circadian window of sensitivity in these species. Entrainment to exogenous melatonin has not previously been demonstrated in a (nonhuman) diurnal mammal. The authors examined the effects of daily melatonin administration (via food) in the diurnal Indian palm squirrel, Funam bulus pennanti. The effects of melatonin or vehicle were examined at two times of day: zeitgeber time 0 (ZT 0: light onset time) and ZT 12 (dark onset time). In addition to melatonin- and vehicle-treated squirrels, there was a third group of squirrels that received no treatment. Squirrels were held initially under 12:12 light-dark (LD) cycles, and melatonin (1 mg/kg) or vehicle was administered in food (a raisin) at either ZT 0 or ZT 12 for a total of 17 days. On the third day of treatment, constant lighting (LL) was imposed. Treatment continued at the same ZTs for a further 14 days. The number of days before free-running commenced under constant conditions was assessed for squirrels in each treatment group. Results showed that regardless of the ZT of administration, the number of days before free-running commenced was significantly greater in melatonin-treated squirrels than in vehicle-treated and untreated squirrels, and there was no difference between vehicle-treated and untreated squirrels. Although there was not a significant difference in the number of days before free-running com menced between the two times of administration, the results showed a trend for greater sensitivity to melatonin at ZT 12. This study has therefore demonstrated that the palm squirrel circadian system is entrainable to melatonin at both times of day tested, ZTs 0 and 12. This finding is in contrast to previous melatonin entrainment studies in other species, where entrainment generally occured at only one phase, around circadian times 10 to 12. Interspecies differences in response to melatonin were discussed.

To examine the role of genetic and environmental factors on sleep behavior in 12-year-old twins matched for family environment.Population-based twin cohort.Participants were assessed in their home environment.One hundred thirty-two adolescent twins comprising 25 monozygotic (MZ) and 41 dizygotic (DZ) twin pairs; aged 12.2 ± 0.1 y (mean ± standard deviation).N/A.For 2 weeks in their home environment, participants wore a wrist activity monitor and completed a daily sleep diary. Sleep diaries included reports of bedtime, wake time, and estimated sleep onset time. Mean timing, duration, and quality of sleep during the 2 weeks were calculated for each individual and compared within twin pairs. MZ twin correlations were higher than the DZ correlations for total sleep time (MZr = 0.64; DZr = 0.38) and sleep onset latency (MZr = 0.83; DZr = 0.53) and significantly higher for wake after sleep onset (MZr = 0.66; DZr = 0.04) and sleep efficiency (MZr = 0.82; DZr = 0.10). Univariate modeling showed additive genetic factors accounted for 65% of the variance in total sleep time, 83% in sleep onset latency, and 52% and 57% of the variance in wake after sleep onset and sleep efficiency, respectively. A predominant influence of shared environment was found on the timing of sleep (67% for sleep start time, 86% for sleep end time).There is a strong genetic influence on the sleep-wake patterns of 12-year-old adolescents. Genes have a greater influence on sleep initiation and sleep maintenance and a smaller role in sleep timing, likely to be influenced by family environment.

About 1.5 million Australians are shift workers. Shift work is associated with adverse health, safety and performance outcomes. Circadian rhythm misalignment, inadequate and poor-quality sleep, and sleep disorders such as sleep apnoea, insomnia and shift work disorder (excessive sleepiness and/or insomnia temporally associated with the work schedule) contribute to these associations. Falling asleep at work at least once a week occurs in 32%-36% of shift workers. Risk of occupational accidents is at least 60% higher for non-day shift workers. Shift workers also have higher rates of cardiometabolic diseases and mood disturbances. Road and workplace accidents related to excessive sleepiness, to which shift work is a significant contributor, are estimated to cost $71-$93 billion per annum in the United States. There is growing evidence that understanding the interindividual variability in sleep-wake responses to shift work will help detect and manage workers vulnerable to the health consequences of shift work. A range of approaches can be used to enhance alertness in shift workers, including screening and treating sleep disorders, melatonin treatment to promote sleep during the daytime, and avoidance of inappropriate use of sedatives and wakefulness-promoters such as modafinil and caffeine. Short naps, which minimise sleep inertia, are generally effective. Shifting the circadian pacemaker with appropriately timed melatonin and/or bright light may be used to facilitate adjustment to a shift work schedule in some situations, such as a long sequence of night work. It is important to manage the health risk of shift workers by minimising vascular risk factors through dietary and other lifestyle approaches.