Author(s): HOUGH, P., NORTH, J.S., PATTERSON, S.D., PEDLAR, C.R. , Institution: ST MARY'S UNIVERSITY, Country: UNITED KINGDOM, Abstract-ID: 1552

INTRODUCTION:
Athletes and military personnel commonly experience consecutive days of sleep restriction (SR) due to their demanding schedules. Consecutive nights of SR impair daytime alertness (1), mood, and motivation (2), which is thought to reduce physical performance (3). However, the effects of cumulative SR on vigilance and physical performance have rarely been explored concurrently. This study investigated the effects of three consecutive nights of SR on vigilance, manual dexterity, and high-intensity physical performance.
METHODS:
Fifteen recreational athletes (12 males, age 37 ± 4.5 y; 3 females, age 39 ± 8.7 y) completed a familiarisation (FAM) trial involving subjective rating scales, the Psychomotor Vigilance Task (PVT), the Perdue Peg Board Test (PPT), a high-intensity intermittent cycling (HIIC) protocol (5 x 10s sprints) and an isometric mid-thigh pull (IMTP). Each participant wore a wrist-worn accelerometer and completed a daily sleep diary throughout the study. The laboratory tests (from FAM) were repeated after three nights of normal sleep (CON) and three nights of SR in a counterbalanced sequence. SR involved participants delaying bedtime by two hours and waking at their usual time for three consecutive nights. Differences between conditions were assessed using paired t-tests and Wilcoxon signed-rank tests.
RESULTS:
Sleep duration was reduced from 7.5 ± 0.6 h (CON) to 5.4 ± 0.64 h (SR) per night, resulting in an average sleep deficit of 6.3 ± 1.5 h across three nights (p < 0.001). Subjective sleep quality decreased by 12% between CON (7.2 ± 1.1) and SR (6.4 ± 1.8, p = 0.04). Sleep efficiency was unchanged between conditions. After SR, the rating of sleepiness (p <0.001), fatigue (p <0.001), and stress (p = 0.02) increased by 60%, 73% and 28%, respectively, and motivation to exercise decreased by 35% (p <0.001). PVT median reaction time decreased by 3.6% (p = 0.02), and response speed increased by 2.6% (p = 0.02) compared to CON. No significant differences were observed for other PVT metrics between conditions. Performance in the manual dexterity tasks, IMTP peak force, and objective metrics measured during the HIIC remained unchanged between CON and SR. However, increased ratings of perceived exertion (2.1%, p = 0.004) and fatigue (10%, p < 0.001) were observed after SR.
CONCLUSION:
Three consecutive nights of SR led to impaired reaction time, reduced motivation, and increased sleepiness, fatigue, and stress ratings. Although manual dexterity and indices of power and force during high-intensity physical tasks did not change after SR, subjective ratings of perceived exertion and fatigue increased. Individuals who regularly experience consecutive days of SR should seek evidence-based interventions, such as caffeine use and napping, to help mitigate the negative effects of SR on vigilance, motivation and perceived exertion.