Examination of the Trident Period Schedule Impact on Self-Reported Sleep and Stress among United States Naval Academy...

Midshipmen attending the U.S. Naval Academy (USNA) are required to awaken early, participate in athletic activities, and attend all academic classes and meals, which may limit opportunities for sleep as well as lead to increased stress. The purpose of this study was to examine the effects of a change to the standard daily schedule on self-reported sleep quality, sleep duration, and perceived stress in USNA midshipmen.

Midshipmen completed the Pittsburgh Sleep Quality Index (PSQI) and Perceived Stress Scale (PSS) at two time points before (T1, T2) and following (T3, T4) a change to their standard daily schedule. The schedule change (1) extended the mid-day break from 105 to 115 minutes for all midshipmen and (2) shifted the standard "lights out" time for freshmen from 2300 to 2200. The earlier lights-out time was recommended for other classes (sophomore, junior, senior) of midshipmen, but only mandated for freshmen. Repeated measures ANOVA was used to examine group differences across time. Cohen's d was used to measure the magnitude of the schedule change effect on differences over time within a group. Two linear mixed models were estimated to examine the directional associations between stress and sleep quality across time.

733 participants (M: n = 511; W: n = 222) completed the questionnaires at T1, though the final sample sizes for those with complete data across all four timepoints for the PSQI and PSS were 359 and 410 midshipmen, respectively. Freshmen reported improved sleep quality from (1) T1 to T3 (6.9 ± 3.0 vs. 5.8 ± 2.7; P = .001, d = 0.27) and (2) T1 to T4 (6.9 ± 3.0 vs. 6.1 ± 3.0; P = .04, d = 0.27). In contrast, juniors reported decreased sleep quality from (1) T1 to T3 (6.8 ± 3.1 vs. 7.7 ± 3.3; P = .013, d = 0.20) and (2) T2 to T3 (6.7 ± 2.9 vs. 7.7 ± 3.3; P = .003, d = 0.29). Freshmen reported increased hours of sleep duration from (1) T1 to T3 (6.4 ± 0.9 vs. 6.7 ± 0.7; P = .002, d = 0.38), (2) T2 to T3 (6.2 ± 1.0 vs. 6.7 ± 0.7; P < .001, d = 0.54), and (3) T2 to T4 (6.2 ± 1.0 vs. 6.6 ± 0.8; P < .001, d = 0.38). In contrast, juniors reported decreased sleep duration from T1 to T4 (6.4 ± 0.9 vs. 6.1 ± 0.9; P = .021, d = 0.31). Seniors reported increased perceived stress from T1 to T3 (11.9 ± 5.5 vs. 13.8 ± 6.5; P = .008, d = 0.27). Lastly, a significant lagged perceived stress × time interaction (P < .001) was found, suggesting that the effect of prior stress on sleep varied across time.

These data suggest that a schedule change that included a mandated earlier "lights out" time resulted in improved sleep quality and duration among freshmen midshipmen, though the magnitudes of change were small. The extent to which this improvement contributes to increased academic performance and physical readiness warrants further attention.