Flexible nap scheduling for cognitive recovery in young adults after acute sleep restriction

Objective This pilot study aimed to explore the effects of supplemental sleep on cognitive recovery after acute sleep deprivation. Methods Thirty healthy adults were randomized to a morning nap group ( n = 15; median age [IQR]: 20.0 [19.0–26.0] years; 33% male) or afternoon nap group ( n = 15; median age: 19.0 [19.0–25.0] years; 53% male). Cognitive assessments included the Karolinska Sleepiness Scale (KSS), reaction time test, Schulte grid test, and N‐BACK test. These tests were administered at a fixed time each day (Day 1). Next, sleep deprivation was performed, and then the cognitive tests were performed again on the second morning (Day 2). Subjects were required to complete morning nap or afternoon nap according to randomized groups. Final cognitive tests were completed on the third day (Day 3). Results (1) Acute sleep deprivation significantly impaired reaction time (Δ = +32.1 ms, p < 0.001) and subjective alertness (KSS score: 3→6, p < 0.001); (2) Supplemental sleep restored performance to baseline levels (all p > 0.05 vs. Day 1); (3) No differences emerged between morning and afternoon naps (all p > 0.05). Conclusions In conclusion, combined nocturnal and daytime sleep effectively restored alertness and attention. Morning and afternoon naps offered comparable benefits, supporting flexible scheduling. These pilot data provide effect size estimates for future trials.