The Winter Contingency - a Sleep Study of Army Aircrews Operating in the Arctic Winter and the Effects of Light Exposure

This study investigated the sleep quality, sleep duration, and mood of soldiers operating in a winter Arctic environment, and the effects of high energy visible (HEV) light exposure. Twenty participants (19 males, one female) at Fort Wainwright, Alaska were recruited to participate in a study. The data collection took place over seven weeks during the winter months. Participants wore sleep-tracking Oura rings throughout the study to assess sleep and wore HEV light-emitting glasses for 30 to 60 minutes upon awakening prior to the start of their duty day; HEV light canvases were also installed in common work areas. Our findings indicated that participants received adequate durations of sleep throughout the study and we saw no significant change (p = 0.356) in sleep durations between the baseline (MD=7.2, IQR=1.78) and light treatment phases of the study (MD=7.07, IQR=1.93). However, the quality of participants sleep may have been lacking as indicated by participant responses on questionnaires. We found significant improvement for profile of mood states (POMS) depressive symptoms (p = 0.039), fatigue (p = 0.074), confusion (p = 0.057) and Becks depression inventory (BDI-II) (p = 0.049) measurements when comparing mid-study and end-of-study questionnaires. The study could not control for the natural increase in daylight throughout the study, which may have played a role in the improvement in mood.