Connection Between Sleep and Psychological Well-Being in U.S. Army Soldiers

Abstract

Introduction: The goal of this exploratory study was to examine the relationships between sleep consistency and workplace resilience among soldiers stationed in a challenging Arctic environment.

Materials and methods: A total of 862 soldiers (67 females) on an Army base in Anchorage, AK, were provided WHOOP 3.0, a validated sleep biometric capture device and were surveyed at onboarding and at the conclusion of the study. Soldiers joined the study from early January to early March 2021 and completed the study in July 2021 (650 soldiers completed the onboarding survey and 210 completed the exit survey, with 151 soldiers completing both). Three comparative analyses were conducted. First, soldiers' sleep and cardiac metrics were compared against the general WHOOP population and a WHOOP sample living in AK. Second, seasonal trends (summer versus winter) in soldiers' sleep metrics (time in bed, hours of sleep, wake duration during sleep, time of sleep onset/offset, and disturbances) were analyzed, and these seasonal trends were compared with the general WHOOP population and the WHOOP sample living in AK. Third, soldiers' exertion, sleep duration, and sleep consistency were correlated with their self-reported psychological functioning. All analyses were conducted with parametric and non-parametric statistics. This study was approved by The University of Queensland Human Research Ethics Committee (Brisbane, Australia) Institutional Review Board.

Results: Because of the exploratory nature of the study, the critical significance value was set at P < .001. Results revealed that: (1) Arctic soldiers had poorer sleep consistency and sleep duration than the general WHOOP sample and the Alaskan WHOOP sample, (2) Arctic soldiers showed a decrease in sleep consistency and sleep duration in the summer compared to that in the winter, (3) Arctic soldiers were less able to control their bedroom environment in the summer than in the winter, and (4) sleep consistency but not sleep duration correlated positively with self-report measures of workplace resilience and healthy social networks and negatively with homesickness.

Conclusions: The study highlights the relationship between seasonality, sleep consistency, and psychological well-being. The results indicate the potential importance of sleep consistency in psychological functioning, suggesting that future work should manipulate factors known to increase sleep consistency to assess whether improved sleep consistency can enhance the well-being of soldiers. Such efforts would be of particular value in an Arctic environment, where seasonality effects are large and sleep consistency is difficult to maintain.

FIGURE 1.

Seasonal differences in sleep consistency. Average sleep consistency of soldiers, the civilians in AK (“Alaskans”), and the age- and gender-matched cohort (“Control”) in the summer and winter. The numbers show the average and the bars represent one SEM.

FIGURE 2.

Seasonal differences in time in bed, hours of sleep, sleep onset and offset, disturbances frequency, and wake duration of soldiers seasonal differences in: Top left; time in bed, P < .001 (total duration from sleep onset to sleep offset, not including time before falling asleep), top center; hours of sleep, P < .001, top right; sleep onset, P < .001, bottom left; sleep offset, P = .01, bottom center; disturbance frequency, P < .001, bottom right; awake duration, P = .92 (total duration of sleep disturbances after sleep onset before sleep offset), among U.S. Army soldiers stationed in AK.

FIGURE 3.

Correlation between exertion, hours of sleep, sleep consistency, and measures of psychological functioning. The numbers represent the correlation coefficient. Each cell is color-coded to represent the P-values associated with the correlation coefficients where white represents P > .05. From light to dark, the colors represent P < .05, P < .01, P < .001, P < .0001.