K. Lucernoni1, S. Kim2, S. Linton2, H. C. Heller3, W. C. Byrnes FACSM2, K. P. Wright2

1Department of Human Physiology, University of Oregon, Eugene, OR; 2Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO; 3Department of Biology, Stanford University, Stanford, CA

Current data suggests that athletes may not obtain adequate sleep while maintaining rigorous training and competition schedules. Daytime napping is a potential strategy to increase total daily sleep time. However, prior exercise and associated increases in core temperature may interfere with napping opportunities. The impact that prior exercise with or without palm cooling has on a daytime napping opportunity has not been investigated. PURPOSE: To determine the impact of prior exercise with or without palm cooling on polysomnography measured variables during a post exercise napping opportunity. METHODS: Twenty male endurance trained athletes were recruited for this randomized cross over study. Participants were involved in a larger protocol examining palm cooling during intermittent and continuous exercise. One-hour daytime napping opportunities followed the continuous exercise bouts (30 min at lactate threshold) with or without cooling and were compared to a control no exercise condition. Polysomnography was used to determine sleep onset, total sleep and slow wave sleep time. Napping opportunities occurred in an environmentally controlled sleep laboratory. Values were reported as mean difference from control [95% CI] while significance was set at p < 0.05. RESULTS: Palm cooling significantly lowered core temperature during exercise but similar core temperatures were observed prior to the napping opportunity. All polysomnography measurements were not different between exercise with and without cooling prior to a nap. When both exercise conditions were compared to the control condition, core temperature and sleep onset were not different, while total sleep (palm cool: 10.7 min [1.1 - 20.3]; no cool: 12.9 min [3.2 - 22.5]) and slow wave sleep time (palm cool: 10.8 min [1.2 - 19.5]; no cool: 14.8 min [4 - 21.3]) were significantly longer. CONCLUSIONS: Exercise with or without palm cooling prior to a one-hour daytime napping opportunity did not impact sleep onset in endurance trained athletes but resulted in increases in total sleep and slow wave sleep time compared to the control napping opportunity. Sleep behaviors were not different between the non-cooling and cooling conditions. These results suggest that prior exercise improves napping behaviors in endurance athletes.

Supported by Pac-12 SAHWBI 1554240

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