Daytime Napping, Endurance Exercise, Mental Fatigue, Sleep
Conditions
Keywords
Sleep, Actigraphy, Napping, Recovery, Running
Brief summary
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.
Interventions
BEHAVIORALMental Fatigue Induction Protocol
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.
BEHAVIORALDaytime Nap
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.
Sponsors
L.U.de.S. Sagl
Universty of Milan
University of Physical Culture in Cracow
University of Rennes
Universita Telematica E-Campus
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)
Masking description
The researcher responsible for data processing and statistical analyses was blinded to condition allocation. Due to the nature of the intervention, participants and the researcher supervising the experimental sessions could not be blinded.
Intervention model description
Participants completed a randomized, counterbalanced, crossover study consisting of two experimental conditions separated by a one-week washout period. In one condition, participants underwent a 30-minute mental fatigue induction protocol before a 30-minute daytime nap; in the control condition, participants completed the nap without the preceding mental fatigue protocol. Each participant served as his own control, and the order of conditions was randomized.
Eligibility
Sex/Gender
MALE
Age
28 Years to 50 Years
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Perceived mental fatigue | 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
| Measure | Time frame | Description |
|---|---|---|
| Actigraphy-Derived nap sleep onset latency | 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. |
| Actigraphy-Derived nap sleep efficiency | 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 |
| Subjective sleepiness | 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." |
| Flanker Task Reaction Time | 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%. |
| Perceived Nap Sleep Quality | 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. |
| Actigraphy-Derived nap start time | 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. |
| Actigraphy-Derived nap time in bed | 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. |
| Actigraphy-Derived nap fragmentation index | 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% |
| Actigraphy-Derived nap total sleep time | 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. |
Countries
Italy
Outcome results
None listed