Strategic daytime napping enhances agility and lowers perceived exertion but does not improve fatigue resistance in adolescent soccer players

Daytime naps are increasingly adopted by athletes to alleviate subjective fatigue and restore alertness, yet their impact on high-intensity anaerobic tasks remains unclear. Both nap duration and circadian timing may modulate psychomotor readiness, perceived exertion, and fatigue resistance, but evidence from team-sport settings is limited. This study aimed to determine how different daytime nap durations (25 vs. 45 min) influence agility, repeated-sprint performance, and psychophysiological responses—including perceived exertion and mood—in adolescent soccer players. Sixteen competitive male adolescent soccer players (all intermediate chronotypes) completed three randomized, crossover sessions: no nap (N0), 25-min nap (N25), and 45-min nap (N45). Nap compliance was objectively verified by actigraphy. After a 60-min post-nap wake-up period, participants performed the Pro Agility Test and a repeated-sprint ability (RSA) protocol. Psychophysiological outcomes included ratings of perceived exertion (RPE), Hooper Index, visual analogue scales (VAS) for alertness, and Profile of Mood States (POMS). Agility improved in a clear dose–response pattern (N0 = 5.40 ± 0.34 s; N25 = 5.18 ± 0.23 s; N45 = 4.98 ± 0.29 s; p < 0.001, ηp 2 = 0.57). RPE was significantly lower after N45 versus N0 (Δ = −1.4; p < 0.01, ηp 2 = 0.45). RSA indices showed no overall condition effect, although best sprint time improved after N45 versus N25 ( p < 0.01) with greater fatigue accumulation across repeated sprints ( p < 0.05). Mood analysis revealed positive associations between fatigue and RPE and negative associations between vigor and RPE, indicating that mood states are associated with perceived exertion. A 45-min early-afternoon nap meaningfully enhanced agility and reduced perceived exertion but did not improve fatigue resistance during repeated sprints. Coaches should weigh the neuromuscular and perceptual benefits of longer naps against potential fatigue trade-offs when designing pre-competition recovery strategies.