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20-minute naps reduce subjective sleepiness and improve cognitive vigilance during extreme sleep deprivation in ultramarathon runners

In an observational field study of 52 finishers of the Ultra-Trail du Mont-Blanc (170 km, ~10,000 m elevation gain), 20-minute naps produced immediate reductions in subjective sleepiness (Karolinska Sleepiness Scale) 1 km post-checkpoint, while cognitive benefits (Psychomotor Vigilance Test reaction times) appeared more gradually, with significantly faster reaction times at subsequent checkpoints. Naps served as an effective reactive strategy to reduce perceived drowsiness and partially protect against late-race performance decline without compromising overall race completion times.

Last updated: Jul 28, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score32/100
Human RCT☆☆☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Do power naps save sleepiness? Cognitive benefits of brief sleep during a 100 miles ultramarathon.

observational

Bourlois V, Boulagnon A, Elsworth-Edelsten C, Ceugniez M, Claeyssen C, Smith M, Comont L, Clergue J, Baron P, Bonduelle C, Pezé T, Hurdiel R · Sleep medicine (2026)

Participants: 52
Duration: During a single 170 km ultramarathon race (multiple editions)
Intervention: 20-minute sleep opportunity (nap) vs. remaining awake at checkpoints CP1-CP3
Outcome: Subjective sleepiness (Karolinska Sleepiness Scale, KSS) and reaction time (Psychomotor Vigilance Test, PVT) at checkpoint entry and 1 km post-checkpoint
Effect Size: N/A
Population: 52 completing runners (mean age 43.9 ± 8.3 years) in the 2022, 2023, and 2024 Ultra-Trail du Mont-Blanc

Result: In an observational field study of 52 finishers of the Ultra-Trail du Mont-Blanc (170 km, ~10,000 m elevation gain), 20-minute naps produced immediate reductions in subjective sleepiness (Karolinska Sleepiness Scale) 1 km post-checkpoint, while cognitive benefits (Psychomotor Vigilance Test reaction times) appeared more gradually, with significantly faster reaction times at subsequent checkpoints. Naps served as an effective reactive strategy to reduce perceived drowsiness and partially protect against late-race performance decline without compromising overall race completion times.

PubMed: 42497815DOI: 10.1016/j.sleep.2026.109159

Mechanism Graph

Nap reduces subjective sleepiness immediately post-nap (1 km checkpoint)
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Cognitive vigilance improvement (faster reaction times) emerges gradually
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Benefits persist to subsequent checkpoints
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Result: Partial protection against late-race performance decline without affecting overall race time

Limitations

  • ⚠Observational design; participants self-selected nap or awake groups, introducing potential selection bias
  • ⚠Nap duration was an opportunity (20 min) rather than controlled actual sleep time; average total sleep across race was 28.4 ± 21.9 min

Frequently Asked Questions

Did the 20-minute naps improve reaction times immediately?▼

No, cognitive benefits (faster reaction times) were not immediate but manifested more gradually, observed only at subsequent checkpoints.

What drove the decision to nap?▼

Nap decisions were primarily driven by subjective sleepiness rather than objective vigilance deficits.

Did napping affect overall race completion times?▼

No, brief naps did not compromise overall race completion times.

How much sleep did runners get on average during the race?▼

Finishers slept an average of 28.4 ± 21.9 minutes total during the race.

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References

  1. 1.Bourlois V, Boulagnon A, Elsworth-Edelsten C, Ceugniez M, Claeyssen C, Smith M, Comont L, Clergue J, Baron P, Bonduelle C, Pezé T, Hurdiel R. "Do power naps save sleepiness? Cognitive benefits of brief sleep during a 100 miles ultramarathon.." Sleep medicine, 2026. PMID: 42497815 DOI: 10.1016/j.sleep.2026.109159
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.