The spectral sensitivity of human circadian phase resetting and melatonin suppression to light changes dynamically with light duration.

Human circadian, neuroendocrine, and neurobehavioral responses to light are mediated primarily by melanopsin-containing intrinsically-photosensitive retinal ganglion cells (ipRGCs) but they also receive input from visual photoreceptors. Relative photoreceptor contributions are irradiance- and duration-dependent but results for long-duration light exposures are limited. We constructed irradiance-response curves and action spectra for melatonin suppression and circadian resetting responses in participants exposed to 6.5-h monochromatic 420, 460, 480, 507, 555, or 620 nm light exposures initiated near the onset of nocturnal melatonin secretion. Melatonin suppression and phase resetting action spectra were best fit by a single-opsin template with lambdamax at 481 and 483 nm, respectively. Linear combinations of melanopsin (ipRGC), short-wavelength (S) cone, and combined long- and medium-wavelength (L+M) cone functions were also fit and compared. For melatonin suppression, lambdamax was 441 nm in the first quarter of the 6.5-h exposure with a second peak at 550 nm, suggesting strong initial S and L+M cone contribution. This contribution decayed over time; lambdamax was 485 nm in the final quarter of light exposure, consistent with a predominant melanopsin contribution. Similarly, for circadian resetting, lambdamax ranged from 445 nm (all three functions) to 487 nm (L+M-cone and melanopsin functions only), suggesting significant S-cone contribution, consistent with recent model findings that the first few minutes of a light exposure drive the majority of the phase resetting response. These findings suggest a possible initial strong cone contribution in driving melatonin suppression and phase resetting, followed by a dominant melanopsin contribution over longer duration light exposures.

Disruptions to sleep and circadian rhythms are associated with poorer athlete mental health in female, but not male, elite Australian Rules footballers.

Elite athletes are vulnerable to sleep and circadian disruption and associated mental health symptoms. This study aimed to investigate sex differences in sleep, circadian rhythms, and mental health, as well as the moderating role of sex in the prediction of mental health, among male professional and female semi-professional elite athletes. Participants were 87 elite Australian Rules football (ARF) athletes (43% female; mean [standard deviation] age 24.0 [4.1] years). Participants completed baseline questionnaires, 2 weeks of sleep/wake monitoring via actigraphy, and a circadian phase assessment (dim-light melatonin onset [DLMO]). Cross-sectional data were collected in training-only Australian Football League (AFL) Men's and Women's pre-season periods, with 53 providing data in two pre-seasons. Female athletes, relative to males, reported poorer mental health (a higher athlete psychological strain score), had a later mid-sleep time (by 28 min), reported a greater preference towards eveningness, and displayed a later circadian phase (by 33 min). For female athletes, lower sleep efficiency and lower sleep regularity were associated with poorer mental health. For female athletes, there were U-shaped relationships between both morningness-eveningness and phase angle (interval between sleep onset and DLMO time) and mental health. No significant relationships were found for male athletes. In summary, elite female ARF athletes reported poorer mental health, relative to males, especially when experiencing sleep or circadian disruption. Lifestyle factors associated with sex differences in ARF professionalism (scheduling, finances, supports) may contribute to these findings. Programmes to improve sleep, circadian alignment, and mental health among female semi-professional elite athletes should be strongly considered.

Subjective awareness of sleepiness while driving in younger and older adults.

Understanding whether drivers can accurately assess sleepiness is essential for educational campaigns advising drivers to stop driving when feeling sleepy. However, few studies have examined this in real-world driving environments, particularly among older drivers who comprise a large proportion of all road users. To examine the accuracy of subjective sleepiness ratings in predicting subsequent driving impairment and physiological drowsiness, 16 younger (21-33 years) and 17 older (50-65 years) adults drove an instrumented vehicle for 2 h on closed loop under two conditions: well-rested and 29 h sleep deprivation. Sleepiness ratings (Karolinska Sleepiness Scale, Likelihood of Falling Asleep scale, Sleepiness Symptoms Questionnaire) were obtained every 15min, alongside lane deviations, near crash events, and ocular indices of drowsiness. All subjective sleepiness measures increased with sleep deprivation for both age groups (p < 0.013). While most subjective sleepiness ratings significantly predicted driving impairment and drowsiness in younger adults (OR: 1.7-15.6, p < 0.02), this was only apparent for KSS, likelihood of falling asleep, and "difficulty staying in the lane for the older adults" (OR: 2.76-2.86, p = 0.02). This may be due to an altered perception of sleepiness in older adults, or due to lowered objective signs of impairment in the older group. Our data suggest that (i) younger and older drivers are aware of sleepiness; (ii) the best subjective scale may differ across age groups; and (iii) future research should expand on the best subjective measures to inform of crash risk in older adults to inform tailored educational road safety campaigns on signs of sleepiness.

A Protocol to Determine Circadian Phase by At-Home Salivary Dim Light Melatonin Onset Assessment.

Internal circadian phase assessment is increasingly acknowledged as a critical clinical tool for the diagnosis, monitoring, and treatment of circadian rhythm sleep-wake disorders and for investigating circadian timing in other medical disorders. The widespread use of in-laboratory circadian phase assessments in routine practice has been limited, most likely because circadian phase assessment is not required by formal diagnostic nosologies, and is not generally covered by insurance. At-home assessment of salivary dim light melatonin onset (DLMO, a validated circadian phase marker) is an increasingly accepted approach to assess circadian phase. This approach may help meet the increased demand for assessments and has the advantages of lower cost and greater patient convenience. We reviewed the literature describing at-home salivary DLMO assessment methods and identified factors deemed to be important to successful implementation. Here, we provide specific protocol recommendations for conducting at-home salivary DLMO assessments to facilitate a standardized approach for clinical and research purposes. Key factors include control of lighting, sampling rate, and timing, and measures of patient compliance. We include findings from implementation of an optimization algorithm to determine the most efficient number and timing of samples in patients with Delayed Sleep-Wake Phase Disorder. We also provide recommendations for assay methods and interpretation. Providing definitive criteria for each factor, along with detailed instructions for protocol implementation, will enable more widespread adoption of at-home circadian phase assessments as a standardized clinical diagnostic, monitoring, and treatment tool.

Rapid Online Data Collection and Reporting to Local Health Departments during the Pandemic: The COVID-19 Outbreak Public Evaluation (COPE) Initiative SARS-CoV-2 Case Surveys.

OBJECTIVES: To develop and implement a pilot online data collection tool to help local health departments with their COVID-19 pandemic response efforts and inform health department actions. DESIGN: The COVID-19 Outbreak Public Evaluation (COPE) was an online survey and was distributed by participating sites to individuals who recently tested positive for SARS-CoV-2. Surveys recorded participant demographics and assessed recent infection risk behaviors (eg, mask use, air travel), vaccination status, sleep and exercise habits, social behaviors and beliefs, and physical and mental health. SETTING: Seven health departments participated in the initiative, which took place during May 1 to September 30, 2022. Identical items were administered to demographically representative samples of adults nationally in the United States within a similar timeframe. PARTICIPANTS: A total of 38 555 participants completed surveys. Responses from participants with recent SARS-CoV-2 infections were compared with respondents from the national surveys who did not have evidence or awareness of prior SARS-CoV-2 infections. MAIN OUTCOME MEASURE: To implement of a process that allows health departments to receive data from local cases and compare this information to national controls during the COVID-19 pandemic. RESULTS: Fifty-four biweekly reports were provided to public health departments between May and September 2022. Information and comparisons within the reports were updated in response to evolving public health priorities for the pandemic response. The initiative helped to guide public health response efforts during the COVID-19 pandemic. Moreover, the receptiveness by local health departments and participants provides evidence to support this data collection and reporting model as a component of the public health response to future emergencies. CONCLUSION: This project demonstrates the feasibility of a centralized, rapid, and adaptive data collection system for local health departments and provides evidence to advocate for data collection methods to help guide local health departments to respond in a timely and effective manner to future public health emergencies.

Treating postpartum insomnia: a three arm randomised controlled trial of cognitive behavioural therapy and light dark therapy.

BACKGROUND: Insomnia symptoms are common during the postpartum period, yet interventions remain scarce. This trial aimed to simultaneously examine the efficacy of cognitive behavioural therapy (CBT) and light dark therapy (LDT), targeting different mechanisms, against treatment-as-usual (TAU), in reducing maternal postpartum insomnia symptoms. METHODS: This three-arm randomised controlled trial recruited from the general community in Australia. Nulliparous females 4-12 months postpartum with self-reported insomnia symptoms [Insomnia Severity Index (ISI) scores >7] were included; severe medical/psychiatric conditions were excluded. Participants were randomised 1:1:1 to CBT, LDT, or TAU stratified by ISI (< or ⩾14) and infant age (< or ⩾8 months). Participants and principal investigators were unblinded. Six-week interventions were delivered via digital materials and telephone. The primary outcome was insomnia symptoms (ISI), assessed pre-, midpoint-, post- (primary endpoint), and one-month post-intervention. Analyses were intention-to-treat using latent growth models. RESULTS: 114 participants (CBT = 39, LDT = 36, TAU = 39; Mage = 32.20 ± 4.62 years) were randomised. There were significantly greater reductions in ISI scores in CBT and LDT (effect sizes -2.01 and -1.52 respectively, p < 0.001) from baseline to post-intervention compared to TAU; improvements were maintained at follow-up. Similar effects were observed for self-reported sleep disturbance. There were greater reductions in fatigue in CBT (effect size = 0.85, p < 0.001) but not LDT (p = 0.11) compared to TAU. Changes in sleepiness, depression, and anxiety were non-significant compared to TAU (all p > 0.08). Four participants (11%) in the LDT group reported headaches, dizziness, or nausea; no others reported adverse events. CONCLUSIONS: Therapist-assisted CBT and LDT were feasible during the first postpartum year; data at post-intervention and 1-month follow-up support their safety and efficacy in reducing postpartum insomnia symptoms.

A brief assessment of eye blink drowsiness immediately prior to or following driving detects drowsiness related driving impairment.

Drowsy driving is a major cause of fatal and serious injury motor vehicle accidents. The inability objectively to assess drowsiness has hindered the assessment of fitness to drive and the development of drowsy driving regulations. This study evaluated whether spontaneous eye blink parameters measured briefly pre- and post-drive could be used to detect drowsy driving impairment. Twelve healthy participants (6 female) drove an instrumented vehicle for 2 h on a closed-loop track during a rested (8-10 h awake) and an extended wake condition (32-34 h awake). Pre- and post-drive, the participants completed a 5 min eye blink task, a psychomotor vigilance task (PVT), and the Karolinska sleepiness scale (KSS). Whole drive impairment was defined as >3.5 lane departures per hour. Severe end of drive impairment was defined as ≥2 lane departures in the last 15 min. The pre-drive % of time with eyes closed best predicted the whole drive impairment (area under the curve [AUC] 0.87). KSS had similar prediction ability (AUC 0.85), while PVT reaction time (AUC 0.72) was less accurate. The composite eye blink parameter, the Johns drowsiness scale was the best retrospective detector of severe end of drive impairment (AUC 0.99). The PVT reaction time (AUC 0.92) and the KSS (AUC 0.93) were less accurate. Eye blink parameters detected drowsy driving impairment with an accuracy that was similar to, or marginally better than, PVT and KSS. As eye blink measures are simple to measure, are objective and have high accuracy, they present an ideal option for the assessment of fitness for duty and roadside drowsiness.

Pilot feasibility testing of biomathematical model recommendations for personalising sleep timing in shift workers.

Sleep disturbances and circadian disruption play a central role in adverse health, safety, and performance outcomes in shift workers. While biomathematical models of sleep and alertness can be used to personalise interventions for shift workers, their practical implementation is undertested. This study tested the feasibility of implementing two biomathematical models-the Phillips-Robinson Model and the Model for Arousal Dynamics-in 28 shift-working nurses, 14 in each group. The study examined the overlap and adherence between model recommendations and sleep behaviours, and changes in sleep following the implementation of recommendations. For both groups combined, the mean (SD) percentage overlap between when a model recommended an individual to sleep and when sleep was obtained was 73.62% (10.24%). Adherence between model recommendations and sleep onset and offset times was significantly higher with the Model of Arousal Dynamics compared to the Phillips-Robinson Model. For the Phillips-Robinson model, 27% of sleep onset and 35% of sleep offset times were within ± 30 min of model recommendations. For the Model of Arousal Dynamics, 49% of sleep onset, and 35% of sleep offset times were within ± 30 min of model recommendations. Compared to pre-study, significant improvements were observed post-study for sleep disturbance (Phillips-Robinson Model), and insomnia severity and sleep-related impairments (Model of Arousal Dynamics). Participants reported that using a digital, automated format for the delivery of sleep recommendations would enable greater uptake. These findings provide a positive proof-of-concept for using biomathematical models to recommend sleep in operational contexts.

The impact of break duration, time of break onset, and prior shift duration on the amount of sleep between shifts in heavy vehicle drivers.

This study aimed to examine the impact of break duration between consecutive shifts, time of break onset, and prior shift duration on total sleep time (TST) between shifts in heavy vehicle drivers (HVDs), and to assess the interaction between break duration and time of break onset. The sleep (actigraphy and sleep diaries) and work shifts (work diaries) of 27 HVDs were monitored during their usual work schedule for up to 9 weeks. Differences in TST between consecutive shifts and days off were assessed. Linear mixed models (followed by pairwise comparisons) assessed whether break duration, prior shift duration, time of break onset, and the interaction between break duration and break onset were related to TST between shifts. Investigators found TST between consecutive shifts (mean [SD] 6.38 [1.38] h) was significantly less than on days off (mean [SD] 7.63 [1.93] h; p < 0.001). Breaks starting between 12:01 and 8:00 a.m. led to shorter sleep (p < 0.05) compared to breaks starting between 4:01 and 8:00 p.m. Break durations up to 7, 9, and 11 h (Australian and European minimum break durations) resulted in a mean (SD) of 4.76 (1.06), 5.66 (0.77), and 6.41 (1.06) h of sleep, respectively. The impact of shift duration prior to the break and the interaction between break duration and time of break were not significant. HVDs' sleep between workdays is influenced independently by break duration and time of break onset. This naturalistic study provides evidence that current break regulations prevent sufficient sleep duration in this industry. Work regulations should evaluate appropriate break durations and break onset times to allow longer sleep opportunities for HVDs.

Perception of Local COVID-19 Transmission and Use of Preventive Behaviors Among Adults with Recent SARS-CoV-2 Infection - Illinois and Michigan, June 1-July 31, 2022.

During the early stages of the COVID-19 pandemic, use of preventive behaviors was associated with perceived risk for contracting SARS-CoV-2 infection (1,2). Over time, perceived risk has declined along with waning COVID-19-related media coverage (3,4). The extent to which communities continue to be aware of local COVID-19 transmission levels and are implementing recommended preventive behaviors is unknown. During June 1-July 31, 2022, health departments in DuPage County, Illinois and metropolitan Detroit, Michigan surveyed a combined total of 4,934 adults who had received a positive test result for SARS-CoV-2 during the preceding 3 weeks. The association between awareness of local COVID-19 transmission and use of preventive behaviors and practices was assessed, both in response to perceived local COVID-19 transmission levels and specifically during the 2 weeks preceding SARS-CoV-2 testing. Both areas had experienced sustained high COVID-19 transmission during the study interval as categorized by CDC COVID-19 transmission levels.* Overall, 702 (14%) respondents perceived local COVID-19 transmission levels as high, 987 (20%) as substantial, 1,902 (39%) as moderate, and 581 (12%) as low; 789 (16%) reported they did not know. Adjusting for geographic area, age, gender identity, and combined race and ethnicity, respondents who perceived local COVID-19 transmission levels as high were more likely to report having made behavioral changes because of the level of COVID-19 transmission in their area, including wearing a mask in public, limiting travel, and avoiding crowded places or events. Continued monitoring of public perceptions of local COVID-19 levels and developing a better understanding of their influence on the use of preventive behaviors can guide COVID-19 communication strategies and policy making during and beyond the pandemic.

The role of circadian phase in sleep and performance during Antarctic winter expeditions.

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.

High sensitivity and interindividual variability in the response of the human circadian system to evening light.

Before the invention of electric lighting, humans were primarily exposed to intense (>300 lux) or dim (<30 lux) environmental light-stimuli at extreme ends of the circadian system's dose-response curve to light. Today, humans spend hours per day exposed to intermediate light intensities (30-300 lux), particularly in the evening. Interindividual differences in sensitivity to evening light in this intensity range could therefore represent a source of vulnerability to circadian disruption by modern lighting. We characterized individual-level dose-response curves to light-induced melatonin suppression using a within-subjects protocol. Fifty-five participants (aged 18-30) were exposed to a dim control (<1 lux) and a range of experimental light levels (10-2,000 lux for 5 h) in the evening. Melatonin suppression was determined for each light level, and the effective dose for 50% suppression (ED50) was computed at individual and group levels. The group-level fitted ED50 was 24.60 lux, indicating that the circadian system is highly sensitive to evening light at typical indoor levels. Light intensities of 10, 30, and 50 lux resulted in later apparent melatonin onsets by 22, 77, and 109 min, respectively. Individual-level ED50 values ranged by over an order of magnitude (6 lux in the most sensitive individual, 350 lux in the least sensitive individual), with a 26% coefficient of variation. These findings demonstrate that the same evening-light environment is registered by the circadian system very differently between individuals. This interindividual variability may be an important factor for determining the circadian clock's role in human health and disease.

Home is where the hustle is: the influence of crowds on effort and home advantage in the National Basketball Association.

Studies have consistently shown crowds contribute to home advantage in the National Basketball Association (NBA) by inspiring home team effort, distracting opponents, and influencing referees. Quantifying the effect of crowds is challenging, however, due to potential co-occurring drivers of home advantage (e.g., travel, location familiarity). Our aim was to isolate the crowd effect using a "natural experiment" created by the Coronavirus disease 2019 (COVID-19) pandemic, which eliminated crowds in 53.4% of 2020/2021 NBA regular season games (N = 1080). Using mixed linear models, we show, in games with crowds, home teams won 58.65% of games and, on average, outrebounded and outscored their opponents. This was a significant improvement compared to games without crowds, of which home teams won 50.60% of games and, on average, failed to outrebound or outscore their opponents. Further, the crowd-related increase in rebound differential mediated the relationship between crowds and points differential. Taken together, these results suggest home advantage in the 2020/2021 NBA season was predominately driven by the presence of home crowds and their influence on the effort exerted to rebound the basketball. These findings are of considerable significance to a league where marginal gains can have immense competitive, financial, and historic consequences.

Mental Health and Substance Use Among Adults with Disabilities During the COVID-19 Pandemic - United States, February-March 2021.

Adults with disabilities, a group including >25% of U.S. adults (1), experience higher levels of mental health and substance use conditions and lower treatment rates than do adults without disabilities* (2,3). Survey data collected during April-September 2020 revealed elevated adverse mental health symptoms among adults with disabilities (4) compared with the general adult population (5). Despite disproportionate risk for infection with SARS-CoV-2, the virus that causes COVID-19, and COVID-19-associated hospitalization and mortality among some adults with disabilities (6), information about mental health and substance use in this population during the pandemic is limited. To identify factors associated with adverse mental health symptoms and substance use among adults with disabilities, the COVID-19 Outbreak Public Evaluation (COPE) Initiative† administered nonprobability-based Internet surveys to 5,256 U.S. adults during February-March 2021 (response rate = 62.1%). Among 5,119 respondents who completed a two-item disability screener, nearly one third (1,648; 32.2%) screened as adults with disabilities. These adults more frequently experienced symptoms of anxiety or depression (56.6% versus 28.7%, respectively), new or increased substance use (38.8% versus 17.5%), and suicidal ideation (30.6% versus 8.3%) than did adults without disabilities. Among all adults who had received a diagnosis of mental health or substance use conditions, adults with disabilities more frequently (42.6% versus 35.3%; p <0.001) reported that the pandemic made it harder for them to access related care or medication. Enhanced mental health and substance use screening among adults with disabilities and improved access to medical services are critical during public health emergencies such as the COVID-19 pandemic.

Health Care Access and Use Among Adults with Diabetes During the COVID-19 Pandemic - United States, February-March 2021.

Diabetes affects approximately one in 10 persons in the United States† and is a risk factor for severe COVID-19 (1), especially when a patient's diabetes is not well managed (2). The extent to which the COVID-19 pandemic has affected diabetes care and management, and whether this varies across age groups, is currently unknown. To evaluate access to and use of health care, as well as experiences, attitudes, and behaviors about COVID-19 prevention and vaccination, a nonprobability, Internet-based survey was administered to 5,261 U.S. adults aged ≥18 years during February-March 2021. Among respondents, 760 (14%) adults who reported having diabetes currently managed with medication were included in the analysis. Younger adults (aged 18-29 years) with diabetes were more likely to report having missed medical care during the past 3 months (87%; 79) than were those aged 30-59 years (63%; 372) or ≥60 years (26%; 309) (p<0.001). Overall, 44% of younger adults reported difficulty accessing diabetes medications. Younger adults with diabetes also reported lower intention to receive COVID-19 vaccination (66%) compared with adults aged ≥60 years§ (85%; p = 0.001). During the COVID-19 pandemic, efforts to enhance access to diabetes care for adults with diabetes and deliver public health messages emphasizing the importance of diabetes management and COVID-19 prevention, including vaccination, are warranted, especially in younger adults.

Mental Health Among Parents of Children Aged <18 Years and Unpaid Caregivers of Adults During the COVID-19 Pandemic - United States, December 2020 and February-⁠March 2021.

Early during the COVID-19 pandemic, nearly two thirds of unpaid caregivers of adults reported adverse mental or behavioral health symptoms, compared with approximately one third of noncaregivers† (1). In addition, 27% of parents of children aged <18 years reported that their mental health had worsened during the pandemic (2). To examine mental health during the COVID-19 pandemic among U.S. adults on the basis of their classification as having a parenting role (i.e., unpaid persons caring for children and adolescents aged <18 years, referred to as children in this report) or being an unpaid caregiver of adults (i.e., persons caring for adults aged ≥18 years),§ CDC analyzed data from cross-sectional surveys that were administered during December 2020 and February-March 2021 for The COVID-19 Outbreak Public Evaluation (COPE) Initiative.¶ Respondents were categorized as parents only, caregivers of adults only, parents-caregivers (persons in both roles), or nonparents/noncaregivers (persons in neither role). Adjusted odds ratios (aORs) for any adverse mental health symptoms, particularly suicidal ideation, were higher among all respondents who were parents, caregivers of adults, or both compared with respondents who were nonparents/noncaregivers and were highest among persons in both roles (parents-caregivers) (any adverse mental health symptoms: aOR = 5.1, 95% confidence interval [CI] = 4.1-6.2; serious suicidal ideation: aOR = 8.2, 95% CI = 6.5-10.4). These findings highlight that parents and caregivers, especially those balancing roles both as parents and caregivers, experienced higher levels of adverse mental health symptoms during the COVID-19 pandemic than adults without these responsibilities. Caregivers who had someone to rely on for support had lower odds of experiencing any adverse mental health symptoms. Additional measures are needed to improve mental health among parents, caregivers, and parents-caregivers.

The impact of the wake maintenance zone on attentional capacity, physiological drowsiness, and subjective task demands during sleep deprivation.

We aimed to investigate the impact of the Wake Maintenance Zone (WMZ) on measures of drowsiness, attention, and subjective performance under rested and sleep deprived conditions. We studied 23 healthy young adults (18 males; mean age = 25.41 ± 5.73 years) during 40 hr of total sleep deprivation under constant routine conditions. Participants completed assessments of physiological drowsiness (EEG-scored slow eye movements and microsleeps), sustained attention (PVT), and subjective task demands every two hours, and four-hourly ocular motor assessment of inhibitory control (inhibition of reflexive saccades on an anti-saccade task). Tests were analyzed relative to dim light melatonin onset (DLMO); the WMZ was defined as the 3 hr prior to DLMO, and the preceding 3 hr window was deemed the pre-WMZ. The WMZ did not mitigate the adverse impact of ~37 hr sleep deprivation on drowsiness, sustained attention, response inhibition, and self-rated concentration and difficulty, relative to rested WMZ performance (~13 hr of wakefulness). Compared to the pre-WMZ, though, the WMZ improved measures of sustained attention, and subjective concentration and task difficulty, during sleep deprivation. Cumulatively, these results expand on previous work by characterizing the beneficial effects of the WMZ on operationally-relevant indices of drowsiness, inhibitory attention control, and self-rated concentration and task difficulty relative to the pre-WMZ during sleep deprivation. These results may inform scheduling safety-critical tasks at more optimal circadian times to improve workplace performance and safety.

In-person vs home schooling during the COVID-19 pandemic: Differences in sleep, circadian timing, and mood in early adolescence.

During the COVID-19 pandemic, schools around the world rapidly transitioned from in-person to remote learning, providing an opportunity to examine the impact of in-person vs remote learning on sleep, circadian timing, and mood. We assessed sleep-wake timing using wrist actigraphy and sleep diaries over 1-2 weeks during in-person learning (n = 28) and remote learning (n = 58, where n = 27 were repeat assessments) in adolescents (age M ± SD = 12.79 ± 0.42 years). Circadian timing was measured under a single condition in each individual using salivary melatonin (Dim Light Melatonin Onset; DLMO). Online surveys assessed mood (PROMIS Pediatric Anxiety and Depressive Symptoms) and sleepiness (Epworth Sleepiness Scale - Child and Adolescent) in each condition. During remote (vs in-person) learning: (i) on school days, students went to sleep 26 minutes later and woke 49 minutes later, resulting in 22 minutes longer sleep duration (all P < .0001); (ii) DLMO time did not differ significantly between conditions, although participants woke at a later circadian phase (43 minutes, P = .03) during remote learning; and (iii) participants reported significantly lower sleepiness (P = .048) and lower anxiety symptoms (P = .006). Depressive symptoms did not differ between conditions. Changes in mood symptoms were not mediated by sleep. Although remote learning continued to have fixed school start times, removing morning commutes likely enabled adolescents to sleep longer, wake later, and to wake at a later circadian phase. These results indicate that remote learning, or later school start times, may extend sleep and improve some subjective symptoms in adolescents.

Home-based light therapy for fatigue following acquired brain injury: a pilot randomized controlled trial.

BACKGROUND AND OBJECTIVES: Fatigue and sleep disturbance are debilitating problems following brain injury and there are no established treatments. Building on demonstrated efficacy of blue light delivered via a lightbox in reducing fatigue and daytime sleepiness after TBI, this study evaluated the efficacy of a novel in-home light intervention in alleviating fatigue, sleep disturbance, daytime sleepiness and depressive symptoms, and in improving psychomotor vigilance and participation in daily productive activity, following injury METHODS: The impact of exposure to a dynamic light intervention (Treatment) was compared to usual lighting (Control) in a randomized within-subject, crossover trial. Outcomes were fatigue (primary outcome), daytime sleepiness, sleep disturbance, insomnia symptoms, psychomotor vigilance, mood and activity levels. Participants (N = 24, M ± SDage = 44.3 ± 11.4) had mild-severe TBI or stroke > 3 months previously, and self-reported fatigue (Fatigue Severity Scale ≥ 4). Following 2-week baseline, participants completed each condition for 2 months in counter-balanced order, with 1-month follow-up. Treatment comprised daytime blue-enriched white light (CCT > 5000 K) and blue-depleted light (< 3000 K) 3 h prior to sleep. RESULTS: Random-effects mixed-model analysis showed no significantly greater change in fatigue on the Brief Fatigue Inventory during Treatment, but a medium effect size of improvement (p = .33, d = -0.42). There were significantly greater decreases in sleep disturbance (p = .004), insomnia symptoms (p = .036), reaction time (p = .004) and improvements in productive activity (p = .005) at end of Treatment relative to Control, with large effect sizes (d > 0.80). Changes in other outcomes were non-significant. CONCLUSIONS: This pilot study provides preliminary support for in-home dynamic light therapy to address sleep-related symptoms in acquired brain injury. TRIAL REGISTRATION: This trial was registered with the Australian and New Zealand Clinical Trials Registry on 13 June 2017, www.anzctr.org.au , ACTRN12617000866303.

The impact of shift work schedules on PVT performance in naturalistic settings: a systematic review.

OBJECTIVE: The Psychomotor Vigilance Test (PVT) is considered the gold standard for detecting sleep loss and circadian misalignment related changes in performance in laboratory and field settings. This short 3-, 5- or 10-min test appraises an individual's sustained vigilant attention on a visual stimulus through reaction time, false starts and performance lapses. The PVT has been widely used as a measure to assess vigilant attention among shift workers, but information evaluating the application and performance of this test in different naturalistic shift work settings is limited. The purpose of this review is to synthesise and evaluate existing literature which has used the PVT to assess and monitor psychomotor performance in response to shift work schedules and rosters performed in real-world settings. METHODS: A systematic search of studies examining PVT performance in response to 24/7 shift work schedules (e.g., day, afternoon, evening and night shifts) performed under naturalistic conditions was conducted. Articles were identified by searching Medline, Embase, CINHAL and PsycINFO databases in April 2020. RESULTS: The search yielded 135 results, of which 16 publications were suitable to be included in this review. Articles were grouped according to when the PVT was applied to a research cohort, which included (a) multiple instances per shift, (b) commencement and cessation of shift and (c) other varying times. CONCLUSIONS: This review suggests PVT performance is typically congruent across studies when the test is applied at generally consistent time intervals. The lack of research concerning the use of the PVT during extended duty shifts (e.g., shifts and on call work > 30 h) is an area for future research.