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Effects of a Short Daytime Nap on the Cognitive Performance: A Systematic Review and Meta-Analysis
Systematic review and meta-analysis (11 studies, 381 adults) finding post-nap cognitive performance improved versus control (pooled effect size ~0.18), with strongest signal for alertness (~0.29), mostly from laboratory nap designs.
Design
- Included: 11 studies (381 participants); search through 2021-08-19
- Setting: predominantly laboratory naps; mean nap duration reported ~55 ± 29 min across included work (wide spread)
- Comparator: no nap control conditions
Pooled cognitive outcomes (abstract; between-group at t1)
- Overall cognition vs control: pooled ES 0.18 (95% CI 0.09–0.27)
- Alertness subdomain: ES 0.29 (95% CI 0.10–0.48)
- Sleep inertia window: performance can look worse immediately after awakening—authors discuss conflicting 0–120 min post-nap windows
- Timing: early-afternoon naps (before ~13:00) associated with better post-nap performance in meta-regression framing (ES ~0.24, CI crosses null in abstract line—inspect full models)
Evidence hygiene
- Not workplace field RCTs—authors caution before operationalising employer nap rooms as prevention
- Pair with cohort nap mortality syntheses on
daytime-nappingfor long-term risk context
Outcomes
- Effect Size (Cohen's d / SMD)0.18d (Cohen's d)
- Effect Size (Cohen's d / SMD)0.29d (Cohen's d)