The Restorative Role of Daytime Naps in Mentally Fatigued Endurance Athletes

L.U.de.S. Sagl11 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Enrollment

Conditions

Mental Fatigue Sleep Endurance Exercise

Interventions

Mental Fatigue Induction ProtocolBEHAVIORAL

Participants completed a 30-minute computerized cognitive task battery designed to induce mental fatigue before the daytime nap. The protocol consisted of three consecutive 10-minute cognitively demanding tasks: a Flanker task, a memory task, and a Stroop task.

Daytime NapBEHAVIORAL

Participants took a 30-minute daytime nap at home between 14:00 and 15:00, at least one hour after lunch, in a quiet and dimly lit room. Nap characteristics were monitored using wrist actigraphy, and perceived sleep quality was assessed after awakening.

Eligibility

Sex: MALEMin age: 28 YearsMax age: 50 Years

Medical Language ↔ Plain English

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

Locations (1)

University of Milan

Milan, Italy

Outcomes

Primary Outcomes

Perceived mental fatigue

Perceived mental fatigue was assessed using a 100-mm visual analogue scale for mental fatigue (VAS-MF), anchored from 0-mm "No mental fatigue" to 100-mm "Maximum mental fatigue." Participants marked the point that best represented their perceived level of mental fatigue.

Time frame: Before the nap, immediately after the nap, and 30 minutes after the nap in each experimental condition.

Secondary Outcomes

Subjective sleepiness

Subjective sleepiness was assessed using the Karolinska Sleepiness Scale (KSS), a 9-point scale ranging from 1, "not sleepy at all," to 9, "extremely sleepy."

Time frame: Before the nap, immediately after the nap, and 30 minutes after the nap

Flanker Task Reaction Time

Accuracy during the computerized Flanker task was calculated as the percentage of correct responses and used as an indicator of executive function performance. Accuracy ranges from 0 to 100%.

Time frame: 30 minutes after the nap in each experimental condition.

Perceived Nap Sleep Quality

Perceived sleep quality after the nap was assessed using a 10-point Likert scale, from 0 to 10, with higher scores indicating better perceived sleep quality.

Time frame: Immediately after the nap in each experimental condition.

Actigraphy-Derived nap start time

Clock time at which the nap period begins, usually identified from the rest interval or sleep diary. Nap start time is expressed as clock time, using the 24-hour format.