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Completed

NCT Number: NCT07580131

The Restorative Role of Daytime Naps in Mentally Fatigued Endurance Athletes

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.

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Key information

Conditions

Mental Fatigue Behavior Behavioral Symptoms Daytime Napping Endurance Exercise Fatigue Pathological Conditions, Signs and Symptoms Signs and Symptoms Sleep

Age range

28 year–50 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

University of Milan

Milan, Italy

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Mental Fatigue Induction Protocol

Behavioral

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 Nap

Behavioral

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.

Primary outcomes

  1. Perceived mental fatigue

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

    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.

Secondary outcomes

  1. Subjective sleepiness

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

    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."

  2. Flanker Task Reaction Time

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

    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%.

  3. Perceived Nap Sleep Quality

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

    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.

  4. Actigraphy-Derived nap start time

    Time frame: During the 30-minute daytime nap in each experimental condition.

    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.

  5. Actigraphy-Derived nap time in bed

    Time frame: During the 30-minute daytime nap in each experimental condition.

    Total time spent in bed or within the defined nap/rest interval, from nap start time to nap end time. Values are expressed in minutes.

  6. Actigraphy-Derived nap total sleep time

    Time frame: During the 30-minute daytime nap in each experimental condition.

    Total duration of epochs scored as sleep during the nap/rest interval. Values are expressed in minutes.

  7. Actigraphy-Derived nap sleep onset latency

    Time frame: During the 30-minute daytime nap in each experimental condition.

    Time elapsed between nap start time and the first epoch scored as sleep. Values are expressed in minutes.

  8. Actigraphy-Derived nap sleep efficiency

    Time frame: During the 30-minute daytime nap in each experimental condition.

    Sleep efficiency is expressed as a percentage, ranging from 0% to 100%, and is calculated as the ratio between total sleep time and time in bed multiplied by 100

  9. Actigraphy-Derived nap fragmentation index

    Time frame: During the 30-minute daytime nap in each experimental condition.

    An index reflecting sleep disruption or restlessness, based on movement and short immobility bouts during the sleep period. Higher values indicate more fragmented sleep. Fragmentation index is expressed as a percentage from 0% to 100%

Sponsors and collaborators

Lead sponsor

L.U.de.S. Sagl

Other

Collaborators

  • Universita Telematica E-Campus
  • University of Physical Culture in Cracow
  • University of Rennes
  • Universty of Milan

Registry information

Official study title

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

Acronym: Nap&Run

Important dates

Study start
2021
Primary completion
2021
Study completion
2021
First posted
May 12, 2026
Registry last updated
May 12, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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