One of the most striking changes in the regulation of sleep-wake behaviour during adolescence is circadian phase delay. Light exposure synchronises circadian rhythms, impacting sleep regulation, however, the influence of real-life light exposure on sleep variations remains less clear. We aimed to describe the sleep and light exposure patterns of high school students with comparable schedules and socio-economic backgrounds, and to evaluate whether there was any association between them, considering chronotype. We analysed five school days and two free days of actigraphy records, from 35 adolescents (24 female, mean age: 16.23 ± 0.60). The sample was described using the Sleep Regularity Index (SRI), chronotype (actigraphy MSFsc), and self-reported diurnal preference (Morning/Evening Scale). Regression models were constructed to assess the impact of light exposure (daytime and nighttime) on subsequent sleep episodes; and to confirm whether the associations could be an indirect consequence of chronotype. Despite following similar routines, the SRI varied considerably (48.25 to 88.28). There was compatibility between the actigraphy proxy for chronotype and the self-reported diurnal preference, extracted using the circadian rhythm scale for adolescents. Less light exposure during the day was associated with later sleep onset and shorter sleep duration. An increase of 100 lux in average daytime light exposure advance of 8.08 minutes in sleep onset and 7.16 min in sleep offset. When the regressions were controlled for chronotype, these associations persisted. These findings facilitate discussions regarding the behavioural aspect of the impact of real-life light exposure on sleep and its potential as a target for interventions aiming to enhance adolescents\' sleep quality.

OBJECTIVE: This study examined longitudinal associations between average physical activity (PA) levels in children and their sleep duration, and whether changes in PA levels are associated with their sleep duration.
METHODS: Data were collected on 108 children at 4 time points: when children were 6, 12, 18, and 24 months of age (44% female, 50% Non-Hispanic White). PA was assessed using accelerometry. Children\'s daytime, nighttime, and 24-hour sleep duration were measured with actigraphy. Linear mixed model analyses estimated the associations between average PA levels over time and changes in PA over time, treating each sleep duration variable as an outcome in separate linear mixed model analyses.
RESULTS: Children with higher total PA levels slept less during the day compared with children with lower total PA levels over the 2-year period. The strength of the relationship between a child\'s PA levels and their 24-hour sleep duration decreased as they approached 24 months of age.
CONCLUSIONS: The results suggest that while PA may be developmentally beneficial overall, it appears that its relationship with sleep duration is not clinically relevant in very young children.

OBJECTIVE: Sleep research in Huntington\'s disease (HD) has primarily focused on manifest HD, with significantly less attention given to premanifest HD (Pre-HD). Therefore, we investigated sleep and rest-activity patterns in people with Pre-HD versus healthy controls (HC).
METHODS: We conducted a cross-sectional study including 36 Pre-HD and 48 HC participants. Pre-HD participants were stratified into three groups according to their proximity to estimated diagnosis, using a cytosine-adenine-guanine (CAG) and current age-based predictive model: NEAR (<9 years to diagnosis), MID (9-15 years to diagnosis) and FAR (>15 years to diagnosis). Sleep and rest-activity patterns were assessed using wrist-worn actigraphy, a sleep diary, and sleep questionnaires.
RESULTS: NEAR and MID groups experienced higher fragmentation index than HC and FAR groups. NEAR and MID groups also exhibited greater WASO than the FAR group. NEAR and MID groups showed lower intra-daily variability (IV) than HC and FAR groups, with the NEAR group also being more active in the most active 10 h (M10). Groups did not differ on subjective sleep measures, inter-daily stability (IS), sleep regularity index, relative amplitude, or amount of activity in the least active 5 h (L5). Considering all Pre-HD participants, fewer years to diagnosis, higher CAG-age-product (CAP) scores (a measure of cumulative exposure to the HD-causing gene mutation) and larger CAG repeat lengths correlated with higher WASO, fragmentation index, L5, IS, and lower sleep efficiency and IV. Higher CAP score correlated with higher M10.
CONCLUSIONS: Despite intact rest-activity patterns and similar subjective sleep quality to HC, greater sleep fragmentation is a prominent and early feature in Pre-HD. Therefore, reducing sleep fragmentation may be a potential target for sleep intervention in HD. Longitudinal studies using larger samples are needed to assess sleep across the disease spectrum and its impact on clinical outcomes, like cognition.

BACKGROUND: People living with HIV (PLWH) often report fatigue even when viral load is suppressed. Obstructive sleep apnea (OSA), which is often associated with fatigue, is common in PLWH, but whether OSA explains fatigue in this population is unknown.
METHODS: Academic university-affiliated HIV and Sleep Medicine Clinics.
METHODS: PLWH, aged 18-65 years, with a body mass index of 20-35 kg/m2 and viral suppression (RNA <200 copies per mL), were recruited to undergo daytime questionnaires, including the Functional Assessment of Chronic Illness Therapy Fatigue Scale and Epworth Sleepiness Scale, 7 days of actigraphy (to determine daily sleep duration and activity amplitude and rhythms), and an in-laboratory polysomnography to assess for the presence and severity of OSA.
RESULTS: Of 120 subjects with evaluable data, 90 (75%) had OSA using the American Academy of Sleep Medicine 3% desaturation or arousal criteria, with an apnea-hypopnea index >5/h. There was no difference in Functional Assessment of Chronic Illness Therapy scores between those with and without OSA, although those with OSA did report more daytime sleepiness as measured using the Epworth Sleepiness Scale. In a multivariable model, predictors of fatigue included more variable daily sleep durations and decreased mean activity counts. Sleepiness was predicted by the presence of OSA.
CONCLUSIONS: OSA was very common in our cohort of PLWH, with those with OSA reporting more sleepiness but not more fatigue. Variability in sleep duration was associated with increased fatigue. Further study is needed to determine if treatment of OSA, or an emphasis on sleep consistency and timing, improves symptoms of fatigue in PLWH.

This study aimed to investigate the changes in sleep quality and quantity among families following the arrival of an autism service dog. We hypothesized that the sleep of the child or adolescent with autism spectrum disorder (assessed objectively with actigraphy and subjectively with a parent-reported sleep diary), and of both parents (assessed by self-reported diaries) would improve after the dog\'s arrival. The sleep of 18 youths (15 boys) aged from 5 to 16 years (M = 8.86), and of their parents (14 mothers, 11 fathers) was assessed for a 5- to 7-day period before (pretest) and eight to ten weeks after the dog\'s arrival (posttest). A designated parent (the same at the pretest and posttest) completed the sleep diary of the child, who wore an actiwatch in the meantime. Significant improvement in most sleep parameters was observed from pretest to posttest for the child and the mother, as reported in the sleep diaries. However, there was no improvement in the child\'s sleep when assessed objectively. Fathers\' sleep duration increased after the dog\'s arrival, when adjusting for the child\'s age. All significant effects had medium to large sizes. This study provides the first quantitative evidence of the positive effect of autism service dogs on the sleep of families. These findings suggest that the dog\'s presence may increase the sense of safety for the child, who would resume sleeping faster or stay in the bedroom after nocturnal awakenings, leading to improved parents\' sleep.

OBJECTIVE: Insomnia is common in children with autism spectrum disorder (ASD). We recently developed and validated the 21-item Pediatric Autism Insomnia Rating Scale (PAIRS). This report explores the associations and agreements between actigraphy and PAIRS.
UNASSIGNED: Children with ASD, with and without sleep problems, were assessed with a battery of parent-rated and clinician measures (N = 134). In a subset (n = 70), a wrist-worn actigraph measured sleep for five consecutive nights. Parents completed logs for scoring sleep intervals. Spearman correlations evaluated associations with the PAIRS and actigraphy indices (sleep onset latency = SOL, wake after sleep onset = WASO, total sleep time = TST, sleep efficiency = SE%). Agreements on \"poor sleepers\" based on PAIRS total score (≥33) and conventional thresholds for TST and SE% were evaluated with Cohen\'s Kappa and McNemar\'s test.
RESULTS: Actigraphy data were averaged over 4.64 ± 0.68 nights in 70 children (mean age = 7.3 ± 2.9, 74.3 % male). There were no significant correlations between PAIRS and any actigraphy indices. On TST, 48.6 % (n = 34) and on SE% 52.9 % (n = 37) were classified as \"poor sleepers\" compared to 32.9 % (n = 23) on PAIRS (kappa = 0.11 for TST and 0.27 for SE%). P-values on McNemar\'s Chi square test for PAIRS with TST and with SE% were 0.072 and 0.011, respectfully.
CONCLUSIONS: These results suggest that actigraphy and PAIRS do not agree. Actigraphy TST captures movement and an estimate of specific sleep parameters. PAIRS is a broader measure that incorporates sleep disturbance and sleep-related impairment.

Sleep and circadian timing systems are constantly regulated by both photic and non-photic signals. Connections between the vestibular nuclei and the biological clock raise the question of the effect of peripheral vestibular loss on daily rhythms, such as the sleep-wake cycle and circadian rhythm. To answer this question, we compared the sleep and rest-activity rhythm parameters of 15 patients with bilateral vestibulopathy (BVP) to those of 15 healthy controls. Sleep and rest-activity cycle were recorded by a device coupling actimetry with the heart rate and actigraphy at home over 7 days. Subjective sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI). Sleep efficiency and subjective sleep quality were significantly reduced, and sleep fragmentation was increased in BVP patients compared to controls. BVP patients displayed a damped amplitude of the rest-activity rhythm and higher sleep fragmentation, reflected by a higher nocturnal activity compared to controls. These results suggest that both rest-activity and sleep cycles are impaired in BVP patients compared to healthy controls. BVP patients seem to have greater difficulty maintaining good sleep at night compared to controls. BVP pathology appears to affect the sleep-wake cycle and disturb the circadian rhythm synchronization. Nevertheless, these results need further investigation to be confirmed, particularly with larger sample sizes.

People who use substances commonly experience sleep disruptions, affecting the regulation of physical and mental health, and presenting a significant barrier to treatment success. Sleep impairments are noted in all phases of substance use; however, differences between subjective versus objective methods used to measure sleep quality have been reported. While polysomnography is the gold-standard for sleep measurement, recent advances in actigraphy may help address the discordance between subjective and objective sleep reports. This systematic review examined emerging evidence (2016-present) for sleep impairment in people who use substances, with the twofold goal of: (1) identifying whether sleep outcomes vary across substance type (alcohol, nicotine, cannabis, cocaine, methamphetamine and opioids); and (2) contrasting results from subjective and objective measures. While some differences between subjective and objective sleep were noted, there was overwhelming evidence of clinically relevant sleep impairment in people who use alcohol, nicotine, cocaine, methamphetamine and opioids, with less consistent results for cannabis. Gaps in the literature are identified and future recommendations are presented, including utilization of common methodological frameworks, identification of mechanisms, and closer examination of sleep across stages of substance use and the interconnection between sleep and return to use.

BACKGROUND: Many disease processes are influenced by circadian clocks and display ~24-hour rhythms. Whether disruptions to these rhythms increase stroke risk is unclear. We evaluated the association between 24-hour rest-activity rhythms, stroke risk, and major poststroke adverse outcomes.
RESULTS: We examined ~100 000 participants from the UK Biobank (aged 44-79 years; ~57% women) assessed with actigraphy (6-7 days) and 5-year median follow-up. We derived (1) most active 10-hour activity counts across the 24-hour cycle and the timing of its midpoint timing; (2) the least active 5-hour count and its midpoint; (3) relative amplitude; (4) interdaily stability; and (5) intradaily variability, for stability and fragmentation of the rhythm. Cox proportional hazard models were constructed for time to (1) incident stroke (n=1652) and (2) poststroke adverse outcomes (dementia, depression, disability, or death). Suppressed relative amplitude (lowest quartile [quartile 1] versus the top quartile [quartile 4]) was associated with stroke risk (hazard ratio [HR], 1.61 [95% CI, 1.35-1.92]; P<0.001) after adjusting for demographics. Later most active 10-hour activity count midpoint timing (14:00-15:26; HR, 1.26 [95% CI, 1.07-1.49]; P=0.007) also had higher stroke risk than earlier (12:17-13:10) participants. A fragmented rhythm (intradaily variability) was also associated with higher stroke risk (quartile 4 versus quartile 1; HR, 1.26 [95% CI, 1.06-1.49]; P=0.008). Suppressed relative amplitude was associated with risk for poststroke adverse outcomes (quartile 1 versus quartile 4; HR, 2.02 [95% CI, 1.46-2.48]; P<0.001). All associations were independent of age, sex, race, obesity, sleep disorders, cardiovascular diseases or risks, and other comorbidity burdens.
CONCLUSIONS: Suppressed 24-hour rest-activity rhythm may be a risk factor for stroke and an early indicator of major poststroke adverse outcomes.

UNASSIGNED: Light exposure techniques have been recommended to combat sleep issues caused by disruption to circadian regularity in the athletic population, although studies are lacking.
UNASSIGNED: A total of 17 professional male Australian Football athletes (age ± SD: 22 ± 3 years) wore a wrist actigraph to measure sleep parameters, and a wearable light sensor to measure melanopic equivalent daylight illuminance (mEDI, in lux) for 14 days. Participants completed three sleep questionnaires at the end of the data collection period and completed well-being surveys 6 times. The Sleep Regularity Index (SRI) for each player was also calculated from actigraphy data. Light exposure data were organised into three different timeframes: morning (wake time + 2 hours), daytime (end of morning to 6 pm), and evening (2 hours leading up to bedtime) for analysis. Repeated measures correlation was conducted for objective sleep measures and mEDI values per timeframe. Pearson\'s correlation was conducted on subjective sleep measures and well-being measures against mEDI values per timeframe.
UNASSIGNED: Higher morning light was associated with significantly (p < 0.001) greater total sleep time (r = 0.31). Higher daytime light exposure was associated with higher subjective sleep quality (r = 0.48, p < 0.05). Higher evening light exposure was associated with higher Athlete Sleep Screening Questionnaire (ASSQ) global scores (r = 0.52, p < 0.05). There were no other significant correlations between light exposure and sleep or well-being measures (p > 0.05).
UNASSIGNED: Higher morning and daylight exposure levels were associated with various positive objective and subjective sleep measures in professional team sport athletes, supporting the need for education on optimising light exposure to improve circadian function, sleep, and health.