NON-PHARMACOLOGICAL INTERVENTIONS TO ENHANCE SLEEP, HEALTH, AND PERFORMANCE IN MILITARY SERVICE MEMBERS

Abstract

ABSTRACT NON-PHARMACOLOGICAL INTERVENTIONS TO ENHANCE SLEEP, HEALTH, AND PERFORMANCE IN MILITARY SERVICE MEMBERS Insufficient sleep is a pervasive problem in the US military, with upwards of 60% of service members sleeping fewer than 6 hours per night. Service members also experience circadian disruption from shift work, early morning training schedules, and global deployments across multiple time zones, which compounds the problems associated with short sleep durations. These conditions impair cognitive function, decrease physical performance, and increase cardiometabolic disease risk, each directly threatening operational readiness. Current approaches to enhance health and performance rely largely on physical fitness programs while countering the effects of insufficient sleep with pharmacological stimulants such as caffeine. Neither of those strategies addresses sleep as the root cause of impairment. Non-pharmacological strategies that do target sleep and circadian biology remain underexplored in military populations. This dissertation reports on two such strategies, bright light therapy and sleep extension, across one scoping review and two experimental studies.The first study is a scoping review of 16 interventional studies involving daytime bright light exposure and cardiometabolic health. The evidence reviewed showed that sunlight exposure modestly improved glycemic control, lipid profiles, and blood pressure in populations with pre-existing risk factors. Artificial bright light therapy showed limited and inconsistent cardiometabolic effects, though it may lower resting heart rate and reduce body fat when combined with exercise. Small sample sizes, low light doses, and inconsistent reporting of light characteristics limited the strength of the conclusions. The second study evaluated the effects of a one-week, home-based light therapy protocol combining morning blue light and evening red light in 20 adults with self-reported sleep difficulties but no clinical sleep disorder. Objective sleep measures assessed by wrist actigraphy did not change significantly. However, participants reported improvements in some aspects of sleep quality and improved morning well-being, including greater alertness, reduced sleepiness, and easier awakening. The third study examined a seven-day sleep extension protocol in 16 Army Reserve Officer Training Corps cadets. Total sleep time increased by approximately one hour per night, and subjective sleepiness decreased. However, objective sleep quality declined significantly. Performance testing showed improvements in bilateral manual dexterity and maximal deadlift strength, while reaction time and endurance measures did not change significantly. The modest sleep gain and the decline in sleep quality that accompanied extended time in bed may explain the limited performance gains. These studies show that non-pharmacological sleep interventions can improve subjective sleep experiences and select performance outcomes, but that interventions targeting a single dimension of sleep health may be insufficient to produce more significant improvements. Strategies that simultaneously address multiple dimensions of sleep health, including quantity, quality, regularity, and timing, are needed to realize the full potential of sleep-related approaches to improved health and performance. Toward that end, this dissertation provides a foundation for developing evidence-based, non-pharmacological strategies to support sleep, health and performance in military service members.