The cumulative influence of sleep time on endurance performance remains unclear. This study examined effects of three consecutive nights of both sleep extension and restriction on endurance cycling performance.
Endurance cyclists/triathletes (n=9) completed a counterbalanced crossover experiment with three conditions; sleep restriction (SR), normal sleep (NS), and sleep extension (SE). Each condition comprised seven days/nights of data collection (-2, -1, D1, D2, D3, D4, +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 prior to 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 analysed using Generalised Estimating Equations.
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; 8.2±0.6h, respectively), and shorter (P<0.001) in the SR condition (4.7±0.8; 4.8±0.8; 4.9±0.4h) compared with NS (7.1±0.8; 6.5±1.0; 6.9±0.7h). Compared with NS, TT performance was slower (P<0.02) on D3 of SR (58.8±2.5 vs 60.4±3.7min) and faster (P<0.02) on D4 of SE (58.7±3.4 vs 56.8±3.1min). RPE was not different between or within conditions. Compared with NS, mood disturbance was higher-, and psychomotor vigilance impaired, following SR. Compared with NS, psychomotor vigilance improved following SE.
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 hours per night to optimise performance.
1Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences. Deakin University, Burwood, Victoria, Australia;
2Physical Education and Sports Science Academic Group, National Institute of Education, Nanyang University, Singapore
Corresponding author: Spencer S. H. Roberts, PhD Candidate School of Exercise and Nutrition Sciences, Deakin University. 221 Burwood Hwy, Burwood, Victoria, Australia, 3125 Email: firstname.lastname@example.org
The results of this study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Results do not constitute endorsement by the American College of Sports Medicine. Spencer Roberts, Wei-Peng Teo, Brad Aisbett, and Stuart Warmington declare they have no conflict of interest. The authors acknowledge the School of Exercise and Nutrition Sciences at Deakin University for funding the study.
Accepted for publication: 9 June 2019.