Effects of Sleep on Training Effectiveness in Soldiers at Fort Leonard Wood, Missouri

Abstract

Abstract : This study examined the effect of alterations in the timing of sleep within the circadian cycle on the amount of total nightly sleep and its influence on various indicators of mood and performance of U.S. Army Soldiers attending Basic Combat Training (BCT) at Fort Leonard Wood, Missouri. The quasi-experimental study design compared Soldiers assigned to one of two training companies: a company using the standard BCT sleep regimen (8:30 p.m. to 4:30 a.m.) or a company using a phase-delayed sleep regimen (11:00 p.m. to 7:00 a.m.), the latter being more in line with the biologically driven sleep-wake patterns of adolescents. Demographic and psychophysiological measures were collected at the start of the study using standard survey instruments and methods. A random sample of approximately 24% of Soldiers wore wrist activity monitors to unobtrusively record sleep quantity and quality. Weekly assessments were made of subjective fatigue and mood throughout BCT. Data on physical fitness, marksmanship, and attrition from BCT were extracted from organizational training records. The study sample was comprised of 392 Soldiers, 209 in the intervention group and 183 in the comparison group. Based on actigraphic data, it was shown that Soldiers on the modified sleep schedule obtained 33 more minutes of total sleep per night than those on the standard sleep schedule. Soldiers in the intervention group reported less total mood disturbance relative to baseline, but the effect size was modest and diminished over the course of BCT. Improvements in Soldier marksmanship performance over a series of record fires was positively correlated with average nightly sleep during the week preceding the record fires, when basic marksmanship tasks were being learned. By the end of BCT, Soldiers in the comparison group were 2.3 times more likely to have occupationally significant fatigue and we