The Restorative Role of Daytime Naps in Mentally Fatigued Endurance Athletes

The Restorative Role of Daytime Naps in Mentally Fatigued Endurance Athletes: a Randomized Controlled Trial

This randomized, counterbalanced crossover study investigated whether a 30-minute daytime nap can mitigate the effects of experimentally induced mental fatigue in amateur master endurance athletes. Male athletes completed two home-based experimental sessions separated by one week: a mental fatigue condition, in which a 30-minute cognitively demanding task battery preceded the nap, and a control condition, in which participants took only the nap. Sleep parameters during the nap were monitored by wrist actigraphy, and perceived sleep quality was assessed after awakening. Subjective sleepiness, perceived mental fatigue, and cognitive performance were evaluated before the nap, immediately after the nap, and/or 30 minutes after the nap.

The study examined whether mental fatigue influenced nap characteristics and whether the nap improved recovery-related outcomes. The main outcomes included actigraphy-derived nap parameters, perceived sleep quality, sleepiness assessed with the Karolinska Sleepiness Scale, perceived mental fatigue assessed using a visual analogue scale, and cognitive performance assessed with a Flanker task.

Inclusion Criteria:

• Male amateur master endurance athletes
• Age between 28 and 50 years
• Peak oxygen uptake (VO₂peak) ≥55 mL·kg-¹·min-¹
• Habitual nocturnal sleep duration of at least 7 hours
• Able and willing to complete both experimental sessions and daytime nap procedures

Exclusion Criteria:

• Diagnosed medical condition or injury
• Diagnosed sleep disorder
• Use of medications or supplements affecting sleep or cognition, including melatonin
• Habitual sleep duration of less than 7 hours per night
• Inability to nap during the experimental sessions