A 20-min nap in athletes changes subsequent sleep architecture but does not alter physical performances after normal sleep or 5-h phase-advance conditions.

Purpose: The aim of the study was to examine the effects of a post-prandial 20 min nap on a short-term physical exercise and subsequent sleep in athletes keeping their usual sleep schedules and in 5-h phase-advance condition.
Methods: Sixteen healthy young male athletes (age 22.2 ± 1.7 years, non-habitual nappers) participated in the study. After a baseline 8-h time in bed in normal and 5-h advanced sleep schedules, a standardized morning and lunch in a laboratory environment, subjects underwent either a nap (20 min of sleep elapsed from 3 epochs of stage 1 or 1 epoch of stage 2), or a rest without sleep by lying in a bed, between 13:00 and 14:00 hours in non-shifted condition or 08:00 and 09:00 hours in shifted condition, after which anaerobic exercises were performed twice 2 h apart. Core body temperature was recorded throughout the study period.
Results: The nap extended sleep onset latency from 6.72 ± 3.83 to 11.84 ± 13.44 min, after shifted condition but did not modify sleep architecture of the post-trial night among athletes, whether shifted or not. Moreover, napping did not improve physical performance but it delayed acrophase and batyphase of core body temperature rhythm parameters.
Conclusion: Napping showed no reliable benefit on short-term performances of athletes exercising at local time or after a simulated jet lag.