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Study Objectives: This study evaluated the efficacy of a brief group-based program of cognitive-behavior therapy for insomnia (CBTi) for older adults suffering from chronic insomnia with short objective sleep relative to those with long sleep duration.Method: Ninety-one adults (male = 43, mean age = 63.34, standard deviation (SD) = 6.41) with sleep maintenance insomnia were selected from a community-based sample. The participants were classified as short sleepers (SS; <6 h total sleep time) or long sleepers (LS; ≥6 h total sleep time) based on one night of home-based polysomnography. Participants were randomly allocated to a 4-week, group-based treatment program of CBTi (N = 30 SS; N = 33 LS) or to a wait-list control condition (N = 9 SS, N = 19 LS). One-week sleep diaries, actigraphy, and a comprehensive battery of questionnaires were used to evaluate the efficacy of CBTi for those with short objective sleep relative to those with long sleep duration. Outcome measures were taken at pretreatment, posttreatment, and a 3-month follow-up.Results: CBTi produced robust and durable improvements in quality of sleep, including reduced wake after sleep onset and improved sleep efficiency. Participants reported a reduction of scores on the Insomnia Severity Index, Flinders Fatigue Scale, Epworth Sleepiness Scale, Daytime Feeling and Functioning Scale, Sleep Anticipatory Anxiety Questionnaire, the Dysfunctional Beliefs and Attitudes about Sleep Scale, and gains on the Sleep Self-Efficacy Scale. All improvements were significant relative to their respective SS or LS wait-list group. The benefits of CBTi were comparable with those who had short and long objective sleep before the treatment.Conclusions: Older adults suffering from chronic insomnia with short objective sleep received comparable therapeutic benefits following CBTi relative to those with long objective sleep duration. [ABSTRACT FROM AUTHOR]

The Antarctic environment presents an extreme variation in the natural light‐dark cycle which can cause variability in the alignment of the circadian pacemaker with the timing of sleep, causing sleep disruption, and impaired mood and performance. This study assessed the incidence of circadian misalignment and the consequences for sleep, cognition, and psychological health in 51 over‐wintering Antarctic expeditioners (45.6 ± 11.9 years) who completed daily sleep diaries, and monthly performance tests and psychological health questionnaires for 6 months. Circadian phase was assessed via monthly 48‐h urine collections to assess the 6‐sulphatoxymelatonin (aMT6s) rhythm. Although the average individual sleep duration was 7.2 ± 0.8 h, there was substantial sleep deficiency with 41.4% of sleep episodes <7 h and 19.1% <6 h. Circadian phase was highly variable and 34/50 expeditioners had sleep episodes that occurred at an abnormal circadian phase (acrophase outside of the sleep episode), accounting for 18.8% (295/1565) of sleep episodes. Expeditioners slept significantly less when misaligned (6.1 ± 1.3 h), compared with when aligned (7.3 ± 1.0 h; p <.0001). Performance and mood were worse when awake closer to the aMT6s peak and with increased time awake (all p <.0005). This research highlights the high incidence of circadian misalignment in Antarctic over‐wintering expeditioners. Similar incidence has been observed in long‐duration space flight, reinforcing the fidelity of Antarctica as a space analog. Circadian misalignment has considerable safety implications, and potentially longer term health risks for other circadian‐controlled physiological systems. This increased risk highlights the need for preventative interventions, such as proactively planned lighting solutions, to ensure circadian alignment during long‐duration Antarctic and space missions. [ABSTRACT FROM AUTHOR]

This study determined whether a blood plasma melatonin rhythm persists in constant photothermal environments in the sleepy lizard, Tiliqua rugosa. It builds upon an earlier investigation which provided equivocal results as to whether an in vivo melatonin rhythm persists in constant dark (DD) and light (LL) and temperature in this species. Using more frequent sampling points and new assay techniques, the present study showed that the melatonin rhythm persisted for at least 6 days at temperatures of 25 and 33°C in constant dark (DD). The melatonin rhythm, however, was largely eliminated in constant light (LL) at 33°C, thereby contradicting some previous findings in other species of reptiles where melatonin levels were apparently insensitive to an unexpected pulse of light at night. These results demonstrate that the sleepy lizard has a persistent, possibly circadian rhythm of melatonin in DD and constant temperature, and that the rhythm is inhibited by LL and constant temperature. Therefore, the sleepy lizard pineal gland may be an independent oscillator capable of driving the melatonin rhythm and be a transducer of the seasonally changing external photothermal environment. [ABSTRACT FROM AUTHOR]

Shorter wavelength light has been shown to be more effective than longer wavelengths in suppressing nocturnal melatonin and phase delaying the melatonin rhythm. In the present study, different wavelengths of light were evaluated for their capacity to phase advance the saliva melatonin rhythm. Two long wavelengths, 595 nm (amber) and 660 nm (red) and three shorter wavelengths, 470 nm (blue), 497 nm (blue/green), and 525 nm (green) were compared with a no-light control condition. Light was administered via a portable light source comprising two light-emitting diodes per eye, with the irradiance of each diode set at 65 μW/cm2. Forty-two volunteers participated in up to six conditions resulting in 15 per condition. For the active light conditions, a 2-hr light pulse was administered from 06:00 hr on two consecutive mornings. Half-hourly saliva samples were collected on the evening prior to the first light pulse and the evening following the second light pulse. The time of melatonin onset was calculated for each night and the difference was calculated as a measure of phase advance. The shorter wavelengths of 470, 495 and 525 nm showed the greatest melatonin onset advances ranging from approximately 40–65 min while the longer wavelengths produced no significant phase advance. These results strengthen earlier findings that the human circadian system is more sensitive to the short wavelengths of light than the longer wavelengths. [ABSTRACT FROM AUTHOR]

Methods for predicting circadian phase have been developed for healthy individuals. It is unknown whether these methods generalize to clinical populations, such as delayed sleep–wake phase disorder (DSWPD), where circadian timing is associated with functional outcomes. This study evaluated two methods for predicting dim light melatonin onset (DLMO) in 154 DSWPD patients using ~ 7 days of sleep–wake and light data: a dynamic model and a statistical model. The dynamic model has been validated in healthy individuals under both laboratory and field conditions. The statistical model was developed for this dataset and used a multiple linear regression of light exposure during phase delay/advance portions of the phase response curve, as well as sleep timing and demographic variables. Both models performed comparably well in predicting DLMO. The dynamic model predicted DLMO with root mean square error of 68 min, with predictions accurate to within ± 1 h in 58% of participants and ± 2 h in 95%. The statistical model predicted DLMO with root mean square error of 57 min, with predictions accurate to within ± 1 h in 75% of participants and ± 2 h in 96%. We conclude that circadian phase prediction from light data is a viable technique for improving screening, diagnosis, and treatment of DSWPD. [ABSTRACT FROM AUTHOR]

Background: In healthy populations, irregular sleep patterns are associated with delayed sleep and poor functional/mood outcomes. Currently, it is unknown whether irregular sleep contributes to poor functional/mood outcomes in individuals with Delayed Sleep-Wake Phase Disorder (DSWPD).Methods: In 170 patients with DSWPD, we collected sleep-wake patterns, dim light melatonin onset (DLMO), and functional/mood outcomes. The Sleep Regularity Index (SRI) and other sleep timing metrics were computed. Correlations of SRI were computed with phase angle (difference between DLMO and desired bedtime), sleep timing and quality variables, daytime function, sleep-related daytime impairment, mood, and insomnia symptom severity. Path analyses assessed whether SRI or total sleep time mediated the associations between sleep onset time and phase angle with daytime functioning, sleep-related impairment, and mood outcomes.Results: Higher SRI was associated with earlier sleep and longer total sleep time, but did not relate to sleep quality, daytime function, or mood outcomes. Path analysis showed that phase angle was directly associated with all outcome variables, whereas sleep onset time was not directly associated with any. SRI mediated the effects of sleep onset time and phase angle on daytime function. Total sleep time mediated the effects of sleep onset time and phase angle on sleep-related impairment.Conclusion: Individuals with DSWPD who have more delayed sleep and a greater phase angle also have more irregular sleep. This suggests that it is not delayed sleep timing per se that drives poor functional outcomes in DSWPD, but rather the timing of sleep relative to circadian phase and resultant irregular sleep patterns. [ABSTRACT FROM AUTHOR]

Background: Delayed Sleep-Wake Phase Disorder (DSWPD) is characterised by sleep initiation insomnia when attempting sleep at conventional times and difficulty waking at the required time for daytime commitments. Although there are published therapeutic guidelines for the administration of melatonin for DSWPD, to our knowledge, randomised controlled trials are lacking. This trial tested the efficacy of 0.5 mg melatonin, combined with behavioural sleep-wake scheduling, for improving sleep initiation in clinically diagnosed DSWPD patients with a delayed endogenous melatonin rhythm relative to patient-desired (or -required) bedtime (DBT).Methods: This randomised, placebo-controlled, double-blind clinical trial was conducted in an Australian outpatient DSWPD population. Following 1-wk baseline, clinically diagnosed DSWPD patients with delayed melatonin rhythm relative to DBT (salivary dim light melatonin onset [DLMO] after or within 30 min before DBT) were randomised to 4-wk treatment with 0.5 mg fast-release melatonin or placebo 1 h before DBT for at least 5 consecutive nights per week. All patients received behavioural sleep-wake scheduling, consisting of bedtime scheduled at DBT. The primary outcome was actigraphic sleep onset time. Secondary outcomes were sleep efficiency in the first third of time in bed (SE T1) on treatment nights, subjective sleep-related daytime impairment (Patient Reported Outcomes Measurement Information System [PROMIS]), PROMIS sleep disturbance, measures of daytime sleepiness, clinician-rated change in illness severity, and DLMO time.Findings: Between September 13, 2012 and September 1, 2014, 307 participants were registered; 116 were randomised to treatment (intention-to-treat n = 116; n = 62 males; mean age, 29.0 y). Relative to baseline and compared to placebo, sleep onset occurred 34 min earlier (95% confidence interval [CI] -60 to -8) in the melatonin group. SE T1 increased; PROMIS sleep-related impairment, PROMIS sleep disturbance, insomnia severity, and functional disability decreased; and a greater proportion of patients showed more than minimal clinician-rated improvement following melatonin treatment (52.8%) compared to placebo (24.0%) (P < 0.05). The groups did not differ in the number of nights treatment was taken per protocol. Post-treatment DLMO assessed in a subset of patients (n = 43) was not significantly different between groups. Adverse events included light-headedness, daytime sleepiness, and decreased libido, although rates were similar between treatment groups. The clinical benefits or safety of melatonin with long-term treatment were not assessed, and it remains unknown whether the same treatment regime would benefit patients experiencing DSWPD sleep symptomology without a delay in the endogenous melatonin rhythm.Conclusions: In this study, melatonin treatment 1 h prior to DBT combined with behavioural sleep-wake scheduling was efficacious for improving objective and subjective measures of sleep disturbances and sleep-related impairments in DSWPD patients with delayed circadian phase relative to DBT. Improvements were achieved largely through the sleep-promoting effects of melatonin, combined with behavioural sleep-wake scheduling.Trial Registration: This trial was registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000425897. [ABSTRACT FROM AUTHOR]

New Findings What is the central question of this study? Disrupting circadian rhythms in rodents perturbs glucose metabolism and increases adiposity. In this study, we asked whether circadian rhythm disruption, induced by exposure of sheep to rapidly alternating photoperiods (RAPs), also disrupts metabolic homeostasis in a large diurnal animal model., What is the main finding and its importance? Exposure to RAPs disrupted central (melatonin and core body temperature) and peripheral rhythmicity (skeletal muscle clock gene expression). This led to reduced nocturnal plasma glucose concentrations, but did not affect glucose tolerance and glucose-stimulated insulin secretion. These results suggest that RAP-induced circadian rhythm disruption has minimal effect on glucose homeostasis in the sheep., Disrupting circadian rhythms in rodents perturbs glucose metabolism and increases adiposity. To determine whether these effects occur in a large diurnal animal, we assessed the impact of circadian rhythm disruption upon metabolic function in sheep. Adult ewes ( n = 7) underwent 3 weeks of a control 12 h light-12 h dark photoperiod, followed by 4 weeks of rapidly alternating photoperiods (RAPs) whereby the time of light exposure was reversed twice each week. Measures of central (melatonin secretion and core body temperature) and peripheral rhythmicity (clock and metabolic gene expression in skeletal muscle) were obtained over 24 h in both conditions. Metabolic homeostasis was assessed by glucose tolerance tests and 24 h glucose and insulin profiles. Melatonin and core body temperature rhythms resynchronized within 2 days of the last photoperiod shift. High-amplitude Bmal1, Clock, Nr1d1, Cry2 and Per3 mRNA rhythms were apparent in skeletal muscle, which were phase advanced by up to 3.5 h at 2 days after the last phase shift, whereas Per1 expression was downregulated at this time. Pparα, Pgc1α and Nampt mRNA were constitutively expressed in both conditions. Nocturnal glucose concentrations were reduced following chronic phase shifts (zeitgeber time 0, −5.5%; zeitgeber time 12, −2.9%; and zeitgeber time 16, −5.7%), whereas plasma insulin, glucose tolerance and glucose-stimulated insulin secretion were not altered. These results demonstrate that clock gene expression within ovine skeletal muscle oscillates over 24 h and responds to changing photoperiods. However, metabolic genes which link circadian and metabolic clocks in rodents were arrhythmic in sheep. Differences may be due to the ruminant versus monogastric digestive organization in each species. Together, these results demonstrate that despite disruptions to central and peripheral rhythmicity following exposure to rapidly alternating photoperiods, there was minimal impact on glucose homeostasis in the sheep. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of split weaning and fence-line boar exposure during lactation on the incidence of lactation oestrus. Large White and Large White×Landrace sows (parity 2.9±0.17; mean±SEM) were housed in conventional farrowing crates from day −4 to 30 post-parturition. Four treatments (n =18) were used: control (SPW0): continuous lactation of 10 piglets with all piglets weaned on day 30 of lactation; and three split wean (SPW) treatments with 3 (SPW3), 5 (SPW5) or 7 (SPW7) of the heaviest piglets removed from the sow on day 18 lactation. From day 18 lactation all sows received 15min daily, fence-line boar exposure in a detection mating area. Fewer sows in the SPW0 treatment (56% (10/18)) expressed a lactation oestrus compared to the SPW3, SPW5, and SPW7 treatments (83%; 89%; 94%, respectively). SPW0 sows had a lower subsequent total born compared to SPW5 or SPW7 sows (8.9±1.1 vs. 12.5±1.0 and 13.1±1.1, respectively). Between day 18 and 30 of lactation, sows in SPW5 and SPW7 gained weight (4.5±1.4 and 1.9±1.4kg, respectively) whereas SPW0 and SPW3 sows lost weight (4.9±1.4 and 2.9±1.4kg, respectively) (P <0.05). Split weaned piglets were heavier at day 17 of age by 1.0kg however by day 40 of age no weight differences were observed between piglets weaned on day 18 compared to day 30 (P <0.05). In conclusion, split weaning coupled with fence-line boar exposure in late lactation induced lactation oestrus in a higher proportion of sows compared to those suckling a normal litter size. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Cognitive behavior therapy is an effective nonpharmacologic treatment for insomnia. However, individualized administration is costly and often results in substantial variability in treatment response across individual patients, particularly so for older adults. Group-based administration has demonstrated impressive potential for a brief and inexpensive answer to the effective treatment of insomnia in the older population. It is important to identify potential predictors of response to such a treatment format to guide clinicians when selecting the most suitable treatment for their patients. The aim of our study was to identify factors that predict subjective sleep quality of older adults following group-based administration of cognitive behavior therapy for insomnia (CBT-I). Methods: Eighty-six adults (41 men; mean age, 64.10y; standard deviation [SD], 6.80) with sleep maintenance or early morning awakening insomnia were selected from a community-based sample to participate in a 4-week group-based treatment program of CBT-I. Participants were required to complete 7-day sleep diaries and a comprehensive battery of questionnaires related to sleep quality and daytime functioning. Hierarchical multiple regression analyses were used to identify factors predicting subjective sleep quality immediately following treatment and at 3-month follow-up. Sleep diaries reported average nightly sleep efficiency (SE), which was used as the outcome measure of sleep quality. Results and conclusions: Participants with the greatest SE following treatment while controlling for pretreatment SE were relatively younger and had more confidence in their ability to sleep at pretreatment. These characteristics may be useful to guide clinicians when considering the use of a group-based CBT-I for sleep maintenance or early morning awakening insomnia in older adults. [Copyright &y& Elsevier]

Abstract: Around a fifth of all road accidents can be attributed to fatigued drivers. Previous studies indicate that driving performance is influenced by time of day and decreases with sustained wakefulness. However, these influences occur naturally in unison, confounding their effects. Typically, when people drive at a poor time of day and with extended wake, their sleep is also restricted. Hence, the aim of the current study was to determine the independent effects of prior wake and time of day on driving performance under conditions of sleep restriction. The driving performance of fourteen male participants (21.8±3.8 years, mean±SD) was assessed during a 10min simulated driving task with speed/lane mean, variability and violations (speeding and crashes) measured. Participants were tested at 2.5h intervals after waking, across 7×28h days with a sleep:wake ratio of 1:5. By forced desynchrony each driving session occurred at 9 doses of prior wake and within 6 divisions of the circadian cycle based on core body temperature. A mixed models ANOVA revealed significant main effects of circadian phase, prior wake and sleep debt on lane violations. In addition, three significant two-way interactions (circadian phase×prior wake, prior wake×sleep debt, sleep debt×circadian phase) and one three-way interaction (circadian×prior wake×sleep debt) were identified. The presence of the large interaction effects shows that the influence of each factor is largely dependent on the magnitude of the other factors. For example, the presence of the time of day influence on driving performance is dependent on the length of prior wake or the presence of sleep debt. The findings suggest that people are able to undertake a low-difficulty simulated drive safely, at least for a short period, during their circadian nadir provided that they have had sufficient sleep and have not been awake too long. [Copyright &y& Elsevier]

Abstract: Subjective ratings of fatigue are increasingly being used as part of a suite of tools to assess fatigue-related risk on the road and in the workplace. There is some debate however, as to whether individuals can accurately gauge their own fatigue states, particularly under conditions of sleep restriction. It is also unclear which references are used by individuals to assess fatigue – for example prior sleep, time of day, workload, or previous ratings. The current study used a sophisticated laboratory protocol to examine the independent contributions of sleep, circadian phase and sleep debt to fatigue ratings. Importantly, participants had no knowledge of time of day, how much sleep they were getting, or how long they were awake. Twenty-eight healthy, young males participated in one of two conditions of a 28h forced desynchrony protocol – severe sleep restriction (4.7h sleep and 23.3h wake) or moderate sleep restriction (7h sleep and 21h wake). Fatigue ratings were provided prior to and following each sleep period using the Samn–Perelli fatigue scale. Repeated measures ANOVAs were used to analyse the effects of circadian phase, sleep dose and study day. Results demonstrated an effect of circadian phase on both pre-sleep and post-sleep fatigue ratings. The significant effect of study day is interpreted as an effect of circadian time, as opposed to accumulating sleep debt. An effect of sleep dose was only seen in post-sleep fatigue ratings. The findings suggest that post-sleep fatigue ratings may be sensitive to prior sleep and may be useful as an indicator of fatigue-related risk, particularly when triangulated with information about recent total sleep time. [Copyright &y& Elsevier]

Summary Subjective alertness may provide some insight into reduced performance capacity under conditions suboptimal to neurobehavioural functioning, yet the accuracy of this insight remains unclear. We therefore investigated whether subjective alertness reflects the full extent of neurobehavioural impairment during the biological night when sleep is restricted. Twenty-seven young healthy males were assigned to a standard forced desynchrony (FD) protocol ( n = 13; 9.33 h in bed/28 h day) or a sleep-restricted FD protocol ( n = 14; 4.67 h in bed/28 h day). For both protocols, subjective alertness and neurobehavioural performance were measured using a visual analogue scale (VAS) and the psychomotor vigilance task (PVT), respectively; both measures were given at various combinations of prior wake and circadian phase (biological night versus biological day). Scores on both measures were standardized within individuals against their respective baseline average and standard deviation. We found that PVT performance and VAS rating deviated from their respective baseline to a similar extent during the standard protocol, yet a greater deviation was observed for PVT performance than VAS rating during the sleep-restricted protocol. The discrepancy between the two measures during the sleep-restricted protocol was particularly prominent during the biological night compared with the biological day. Thus, subjective alertness did not reflect the full extent of performance impairment when sleep was restricted, particularly during the biological night. Given that subjective alertness is often the only available information upon which performance capacity is assessed, our results suggest that sleep-restricted individuals are likely to under-estimate neurobehavioural impairment, particularly during the biological night. [ABSTRACT FROM AUTHOR]

Abstract: The amount of sleep obtained between shifts is influenced by numerous factors including the length of work and rest periods, the timing of the rest period relative to the endogenous circadian cycle and personal choices about the use of non-work time. The current study utilised a real-world live-in mining environment to examine the amount of sleep obtained when access to normal domestic, family and social activities was restricted. Participants were 29 mining operators (26 male, average age 37.4±6.8 years) who recorded sleep, work and fatigue information and wore an activity monitor for a cycle of seven day shifts and seven night shifts (both 12h) followed by either seven or fourteen days off. During the two weeks of work participants lived on-site. Total sleep time was significantly less (p <0.01) while on-site on both day (6.1±1.0h) and night shifts (5.7±1.5h) than days off (7.4±1.4h). Further, night shift sleep was significantly shorter than day-shift sleep (p <0.01). Assessment of subjective fatigue ratings showed that the sleep associated with both days off and night shifts had a greater recovery value than sleep associated with day shifts (p <0.01). While on-site, participants obtained only 6h of sleep indicating that the absence of competing domestic, family and social activities did not convert to more sleep. Factors including shift start times and circadian influences appear to have been more important. [ABSTRACT FROM AUTHOR]

The vertebrate pineal gland is the primary source of melatonin, the rhythmic secretion of which is influenced by environmental light and temperature, thereby providing animals with information about seasonally changing photoperiod and thermoperiod. Although pineal glands are present in the majority of vertebrate species, a discrete organ is reported to be absent in the Crocodilia. However, if the melatonin rhythm is crucial to the survival of the organism, it would be expected that the rhythm would be present in crocodiles. In the present study, we measured blood plasma melatonin over a 30-h period in aestivating Australian freshwater crocodiles ( Crocodylus johnstoni) in their natural habitat at the end of the dry season (November) and found no discernible melatonin rhythm. However, another group of captive-reared C. johnstoni, maintained under natural light and temperature cycles and sampled in the early dry season (June) showed a clear melatonin rhythm. These results suggest that there is either an extrapineal source of melatonin in this crocodile species or that there is melatonin producing tissue elsewhere which heretofore has not been discovered. Further studies are needed to determine why the melatonin rhythm is intermittently expressed and whether this may be related to seasonal changes in the expression of the rhythm linked to tropical environments. [ABSTRACT FROM AUTHOR]

The phenomenon of spinal deformity in the pinealectomized chicken has led researchers to postulate a disturbance of melatonin activity as a potential cause of adolescent idiopathic scoliosis (AIS). More recently, structural differences between curves seen in this model and those seen in scoliosis have been highlighted suggesting the deformities observed are not as similar as first thought. We examined melatonin levels, and the radiological and histological characteristics of scoliosis after pinealectomy in chickens. They underwent pinealectomy (P) at 2 days of age, sham surgery (S) or served as controls (C). Mean melatonin levels were 32.9 pmol/L (P), 175 pmol/L (S) and 227.3 pmol/L (C). Scoliosis developed in 75% of chickens after pinealectomy and 38% after a sham procedure. Nineteen percent of unoperated controls also developed scoliosis. A lower melatonin level was associated with the development of scoliosis (p < or = 0.001), but exceptions were seen with levels up to 265 pmol/L observed in one case. Most of the curves occurring spontaneously and after sham surgery and almost half after pinealectomy were short angular curves: distinct from those resembling idiopathic scoliosis. These occur over one or two segments and are characterized by marked apical wedging, frequently associated with subluxation or dislocation. The intervertebral joint in the chicken is more like a synovial joint histologically than an intervertebral disc. This study highlights important differences between the chicken and the human, and between their respective spinal deformities. Caution is advised when drawing conclusions regarding the pathogenesis of AIS from this model. [ABSTRACT FROM AUTHOR]