Relationship Between Objective Measures of Sleep and Nocturnal Cardiovascular Physiology and Swimming Performance in Collegiate Female Athletes: A Bayesian Analysis.

Vatne, EA, Cencer, D, Vatne, M, Pulvermacher, K, Saenz, C, Kraemer, WJ, Robinson, B, Jones, P, Quebedeaux, N, Sprague, R, Dial, M, Carpenter, T, and Hagen, J. Relationship between objective measures of sleep and nocturnal cardiovascular physiology and swimming performance in collegiate female athletes: A Bayesian analysis. J Strength Cond Res XX(X): 000-000, 2026-There is substantial evidence that sleep influences athletic performance; however, relationships with real-world competition outcomes remain unclear. Therefore, the purpose of this study was to explore the associations between objectively measured sleep, nocturnal cardiovascular physiology on the night before competition, and swim performance in female collegiate athletes. Female swimmers (n = 11) who wore a sleep monitoring device the night before competition, competed in the 200-yard freestyle (short course yard), and had ≥21 of 28 prior nights of valid data were included. Sleep metrics included total sleep time (TST), time in bed (TiB), and sleep efficiency (SE), whereas nocturnal cardiovascular metrics included heart rate variability (HRV) and resting heart rate (RHR) standardized as individualized z-scores. Race times were obtained from a publicly available database. Bayesian linear mixed-effects models estimated posterior probabilities of performance improvement. Results indicated a high probability that greater TST and TiB were associated with faster race times, with substantial support for improvements of at least 1 second per additional hour of sleep. In contrast, SE, HRV, and RHR showed low posterior evidence of meaningful associations with performance. These findings extend prior sleep and performance literature that has been confined to proxy assessments of athletic performance in controlled settings to real-world competition that should inform athlete education, emphasizing the importance of sufficient sleep opportunity and duration before competition.