Extended Sleep Maintains Endurance Performance Better than Normal or Restricted Sleep

Purpose The cumulative influence of sleep time on endurance performance remains unclear. This study examined the effects of three consecutive nights of both sleep extension (SE) and sleep restriction (SR) on endurance cycling performance. Methods Endurance cyclists/triathletes (n = 9) completed a counterbalanced crossover experiment with three conditions: SR, normal sleep (NS), and SE. Each condition comprised seven days/nights of data collection (-2, -1, D1, D2, D3, D4, and +1). Sleep was monitored using actigraphy throughout. Participants completed testing sessions on days D1-D4 that included an endurance time-trial (TT), mood, and psychomotor vigilance assessment. Perceived exertion (RPE) was monitored throughout each TT. Participants slept habitually before D1; however, time in bed was reduced by 30% (SR), remained normal (NS), or extended by 30% (SE) on nights D1, D2, and D3. Data were analyzed using generalized estimating equations. Results On nights D1, D2, and D3, total sleep time was longer (P < 0.001) in the SE condition (8.6 +/- 1.0, 8.3 +/- 0.6, and 8.2 +/- 0.6 h, respectively) and shorter (P < 0.001) in the SR condition (4.7 +/- 0.8, 4.8 +/- 0.8, and 4.9 +/- 0.4 h) compared with NS (7.1 +/- 0.8, 6.5 +/- 1.0, and 6.9 +/- 0.7 h). Compared with NS, TT performance was slower (P < 0.02) on D3 of SR (58.8 +/- 2.5 vs 60.4 +/- 3.7 min) and faster (P < 0.02) on D4 of SE (58.7 +/- 3.4 vs 56.8 +/- 3.1 min). RPE was not different between or within conditions. Compared with NS, mood disturbance was higher, and psychomotor vigilance impaired, after SR. Compared with NS, psychomotor vigilance improved after SE. Conclusion Sleep extension for three nights led to better maintenance of endurance performance compared with normal and restricted sleep. Sleep restriction impaired performance. Cumulative sleep time affects performance by altering the perceived exertion of a given exercise intensity. Endurance athletes should sleep >8 h per night to optimize performance.