REF-943 · Roberts et al., 2019 · Medicine & Science in Sports & Exercise, Vol. · Paper · PubMed

Extended Sleep Maintains Endurance Performance Better than Normal or Restricted Sleep

Blimited evidenceMeasured on trained to highly trained athletesWritten before October 2026, being re-checked

Nine endurance cyclists/triathletes completed three conditions in a counterbalanced crossover: sleep restriction (SR), normal sleep (NS) and sleep extension (SE).

Each condition had four consecutive testing days (D1-D4) with an endurance time trial (TT), mood and psychomotor vigilance testing; time in bed on nights D1, D2 and D3 was reduced by 30% (SR), kept normal (NS) or extended by 30% (SE). Sleep was monitored by actigraphy. Compared with NS, the TT was slower on D3 of SR and faster on D4 of SE; RPE did not differ.

Mood disturbance was higher and vigilance impaired after SR; vigilance improved after SE. The authors conclude that endurance athletes should sleep >8 h per night to optimize performance.

Participants

Endurance cyclists/triathletes, n = 9. Age, sex and training level are not given in the abstract.

Protocol

Counterbalanced crossover: SR, NS, SE. Each condition = seven days/nights of data collection (-2, -1, D1, D2, D3, D4, +1).
Habitual sleep before D1; time in bed reduced by 30% (SR), normal (NS) or extended by 30% (SE) on nights D1, D2 and D3.
Testing on days D1-D4: endurance time trial with RPE throughout, mood, psychomotor vigilance.
Sleep by actigraphy; generalized estimating equations.

Key Results

Total sleep time on nights D1, D2, D3 — SE: 8.6 ± 1.0, 8.3 ± 0.6 and 8.2 ± 0.6 h; SR: 4.7 ± 0.8, 4.8 ± 0.8 and 4.9 ± 0.4 h; NS: 7.1 ± 0.8, 6.5 ± 1.0 and 6.9 ± 0.7 h (both P < 0.001 vs NS).
TT slower on D3 of SR than NS: 58.8 ± 2.5 vs 60.4 ± 3.7 min (NS vs SR, P < 0.02).
TT faster on D4 of SE than NS: 58.7 ± 3.4 vs 56.8 ± 3.1 min (NS vs SE, P < 0.02).
RPE was not different between or within conditions.
After SR: higher mood disturbance and impaired psychomotor vigilance vs NS. After SE: improved psychomotor vigilance vs NS.

Practical Application

"Does a few short nights really cost me, and does extra sleep help?" In 9 endurance cyclists/triathletes tested on four consecutive days, cutting time in bed by 30% (about 4.7-4.9 h of sleep) slowed the time trial by D3 (60.4 vs 58.8 min), and extending it by 30% (about 8.2-8.6 h) made it faster by D4 (56.8 vs 58.7 min). The effect built over nights: it showed after two to three nights, not after the first.
RPE was the same while the work done differed, so the athlete will not feel the loss as a harder effort. Inference, not tested here: after several short nights, judge a key session by its output, and expect a lower one at the usual effort.
Before a block of hard days or a multi-day event, add time in bed for the nights before and during. The authors' advice is >8 h of sleep per night.
Not from this paper; the base's own practice: after short nights a missed or weak key session is moved, not stacked (SYNTH-72). The pooled cost of acute sleep loss is in REF-204.

Limitations

n = 9; sex and training level not given in the abstract.
Time in bed was manipulated for three nights only; longer-term restriction or extension is not tested.
Daily time trials: the outcome is how well performance was maintained across consecutive days, not a single fresh effort.
The stated mechanism (altered perceived exertion at a given intensity) is the authors' interpretation.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

crossover with n = 9