Insufficient Sleep and Behavioral Health in the Military: A 5-Country Perspective

PURPOSE OF REVIEW

The goal of this paper was to highlight the degree to which sleep, behavioral health, and leader involvement were interrelated using data from militaries in five English-speaking countries: Australia, Canada, New Zealand, the UK, and the United States.

RECENT FINDINGS

Many service members reported sleeping fewer than the recommended 7 h/night: 34.9%, 67.2%, and 77.2% of respondents from New Zealand, Canada, and the United States, respectively. Countries reporting shorter sleep duration also reported fewer insomnia-related difficulties, likely reflecting higher sleep pressure from chronic sleep loss. Across all countries, sleep problems were positively correlated with behavioral health symptoms. Importantly, leader promotion of healthy sleep was positively correlated with more sleep and negatively correlated with sleep problems and behavioral health symptoms. Insufficient sleep in the military is ubiquitous, with serious implications for the behavioral health and functioning of service members. Leaders should attend to these risks and examine ways to promote healthy sleep in service members.

The effect of 24-hour sleep deprivation on subjective time perception

In this study, we investigated the effect of 24-h total sleep deprivation on subjective time perception. Twenty-five participants aged 18-35 years (13 female and 12 male) were recruited. Time perception and cognitive assessments were performed twice: after a regular night's sleep and following a 24-h sleep deprivation. The retrospective and prospective tasks were used to measure time perception. In order to prevent order effect, the test orders were randomized. The Stroop test and the Wechsler Memory Scale-III were used to evaluate attention, processing speed, and memory. The repeated measures ANOVA was used to examine gender-by-sleep deprivation interactions on time perception. We found that retrospective time perception was significantly prolonged after sleep deprivation (p < 0.05). Women had a shorter prospective time estimation rate after adequate sleep than men, but this difference disappeared after sleep deprivation. The Stroop test showed improvement in cognitive flexibility after sleep deprivation (p < 0.05), and short-term or working memory appeared unaffected by one night of sleep deprivation. There was a negative correlation between sleepiness rate and working memory function in female subgroup. The results suggest that even short-term sleep deprivation can significantly affect time perception, which may have important implications in critical situations.

Sleep in times of crises: A scoping review in the early days of the COVID-19 crisis

During the early days of the pandemic and in the context of a seemingly unknown global threat, several potential major sleep disruptors were identified by sleep researchers and practitioners across the globe. The COVID-19 pandemic combined several features that, individually, had been shown to negatively affect sleep health in the general population. Those features included state of crisis, restrictions on in-person social interactions, as well as financial adversity. To address the lack of a comprehensive summary of sleep research across these three distinctive domains, we undertook three parallel systematic reviews based on the following themes: 1) Sleep in times of crises; 2) Sleep and social isolation; and 3) Sleep and economic uncertainty. Using a scoping review framework, we systematically identified and summarized findings from these three separated bodies of works. Potential moderating factors such as age, sex, ethnicity, socioeconomic status, psychological predisposition, occupation and other personal circumstances are also discussed. To conclude, we propose novel lines of research necessary to alleviate the short- and long-term impacts of the COVID-19 crises and highlight the need to prepare the deployment of sleep solutions in future crises.

Genetic Markers of Differential Vulnerability to Sleep Loss in Adults

In this review, we discuss reports of genotype-dependent interindividual differences in phenotypic neurobehavioral responses to total sleep deprivation or sleep restriction. We highlight the importance of using the candidate gene approach to further elucidate differential resilience and vulnerability to sleep deprivation in humans, although we acknowledge that other omics techniques and genome-wide association studies can also offer insights into biomarkers of such vulnerability. Specifically, we discuss polymorphisms in adenosinergic genes (ADA and ADORA2A), core circadian clock genes (BHLHE41/DEC2 and PER3), genes related to cognitive development and functioning (BDNF and COMT), dopaminergic genes (DRD2 and DAT), and immune and clearance genes (AQP4, DQB1*0602, and TNFα) as potential genetic indicators of differential vulnerability to deficits induced by sleep loss. Additionally, we review the efficacy of several countermeasures for the neurobehavioral impairments induced by sleep loss, including banking sleep, recovery sleep, caffeine, and naps. The discovery of reliable, novel genetic markers of differential vulnerability to sleep loss has critical implications for future research involving predictors, countermeasures, and treatments in the field of sleep and circadian science.

Feasibility of sleep extension and its effect on cardiometabolic parameters in free-living settings: a systematic review and meta-analysis of experimental studies

AIMS

Inadequate sleep is a global health issue and has been associated with an increased risk for cardiovascular diseases. As a part of sleep hygiene, intentional lengthening of night-time sleep duration (i.e. sleep extension) might be a behavioural intervention to improve cardiometabolic health. To examine the feasibility of sleep extension and its effects on cardiometabolic parameters in free-living settings.

METHODS AND RESULTS

This review was registered in PROSPERO (CRD42019146174). Five databases were searched. Only experimental studies conducted in adults without a diagnosis of sleep disorder were included. The pooled mean difference was calculated by the inverse variance method. Narrative summaries were also used. Thirteen studies from 11 trials were included. The intervention ranged from 3 days to 6 weeks. Sleep extension increased total sleep time by 51 min [95% confidence interval (CI) 39-63]. Overall, sleep extension did not result in significant changes in blood pressure. However, sub-group analysis revealed that when 24 h mean blood pressure was obtained among those with pre-hypertension or Stage 1 hypertension, sleep extension reduced systolic (weighted mean difference = -7.8 mm/Hg; 95% CI -10.6 to -4.9), and diastolic blood pressure (weighted mean difference = -4.2 mm/Hg; 95% CI -6.7 to -1.8). The pooled effects on fasting glucose and insulin resistance were not significant. The effect of sleep extension on other parameters (e.g. heart rate) was not consistent.

CONCLUSION

Sleep extension is feasible and could increase sleep in free-living settings. Sleep extension shows promise for reducing 24 h mean blood pressure among those with pre-hypertension or hypertension. More large-scale studies are needed to examine its long-term effects.