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Completed

NCT Number: NCT07700576

Effects of Different Nap Durations on Volleyball Performance and EEG Activity Following Mental Fatigue

Mental fatigue is known to impair cognitive and physical performance in athletes, but the effectiveness of different nap durations in counteracting these effects remains unclear. The purpose of this randomized crossover study is to investigate the effects of mental fatigue and different nap durations (20, 40, 60, and 90 minutes) on volleyball-specific performance and electroencephalographic (EEG) activity in trained male volleyball players. Mental fatigue is induced using a 15-minute Stroop task. Performance outcomes include the Volleyball Agility Test (VAT) and Countermovement Jump (CMJ), while cortical activity is assessed using resting-state EEG recordings. The findings are expected to improve understanding of the neurophysiological mechanisms underlying mental fatigue and recovery and to provide evidence-based recommendations regarding optimal nap duration for athletes.

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Key information

Conditions

Mental Fatigue Behavior Behavioral Symptoms Fatigue Pathological Conditions, Signs and Symptoms Recovery Signs and Symptoms Sport Performance Volleyball

Age range

19 year–22 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Inonu University, Faculty of Sport Sciences

Malatya, 44280, Turkey (Türkiye)

About this study

Mental fatigue has emerged as an important factor influencing athletic performance by impairing attention, executive function, decision-making, and motor performance. Volleyball is a sport requiring rapid cognitive processing, agility, explosive power, and precise motor control, making athletes particularly vulnerable to the detrimental effects of mental fatigue. Although daytime napping has been proposed as an effective recovery strategy, the optimal nap duration for restoring sport performance and brain activity following mental fatigue remains uncertain.

This study employs a randomized crossover repeated-measures design in which each participant completes six experimental conditions: Control, Mental Fatigue, Mental Fatigue followed by a 20-minute nap, Mental Fatigue followed by a 40-minute nap, Mental Fatigue followed by a 60-minute nap, and Mental Fatigue followed by a 90-minute nap. Mental fatigue is induced using a standardized 15-minute computerized Stroop task. A 72-hour washout period is maintained between consecutive experimental sessions.

Primary assessments include volleyball-specific agility performance, countermovement jump performance, and resting-state electroencephalographic (EEG) recordings obtained before and after mental fatigue and following the nap intervention. EEG analyses focus on spectral power in the delta, theta, alpha, and beta frequency bands as well as Theta/Alpha and Theta/Beta ratios.

The study aims to determine whether different nap durations differentially improve volleyball-specific performance and cortical activity following mental fatigue. The results are expected to provide practical recommendations for coaches and athletes regarding evidence-based recovery strategies while contributing to a better understanding of the neurophysiological mechanisms underlying mental fatigue and post-nap recovery.

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Male volleyball players aged 19 to 22 years.
  • Minimum of 3 years of regular volleyball training and active participation in organized training.
  • Apparently healthy and free from neurological, cardiovascular, musculoskeletal, or metabolic disorders.
  • Normal or corrected-to-normal vision.
  • Willing to provide written informed consent.
  • Agreed to refrain from strenuous exercise, alcohol, and caffeine for at least 24 hours before each experimental session.

Exclusion criteria

  • History of neurological, psychiatric, cardiovascular, or musculoskeletal disorders.
  • Current injury affecting sports performance.
  • Use of medications known to influence cognitive function, sleep, or central nervous system activity.
  • Diagnosed sleep disorders.
  • Failure to comply with study procedures or pre-test instructions.
  • Inability to complete all experimental sessions.

Treatment and study plan

Mental Fatigue Induction

Behavioral

Mental fatigue was induced using a standardized 15-minute computerized Stroop Color-Word Task designed to increase cognitive load and induce mental fatigue before performance and EEG assessments.

Control condition

Other

Participants watched a neutral documentary for 15 minutes without mental fatigue induction or daytime nap intervention before EEG and performance assessments.

Daytime Nap 20 Minutes

Behavioral

Participants underwent a supervised 20-minute daytime nap following mental fatigue induction in a quiet, darkened room before post-intervention EEG and performance assessments.

Daytime Nap 40 Minutes

Behavioral

Participants underwent a supervised 40-minute daytime nap following mental fatigue induction in a quiet, darkened room before post-intervention EEG and performance assessments.

Daytime Nap 60 Minutes

Behavioral

Participants underwent a supervised 60-minute daytime nap following mental fatigue induction in a quiet, darkened room before post-intervention EEG and performance assessments.

Daytime Nap 90 Minutes

Behavioral

Participants underwent a supervised 90-minute daytime nap following mental fatigue induction in a quiet, darkened room before post-intervention EEG and performance assessments.

Primary outcomes

  1. EEG Spectral Power

    Time frame: At baseline, immediately after the mental fatigue task, and immediately after completion of the assigned intervention during each experimental session.

    Resting-state electroencephalographic (EEG) activity was recorded from the Fz, Cz, Pz, O1, and O2 electrode sites. Power spectral density was analyzed for the delta (1-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), and beta (13-30 Hz) frequency bands. All frequency-band power values were expressed in microvolts squared per hertz (µV²/Hz).

  2. EEG Theta/Alpha Ratio

    Time frame: At baseline, immediately after the mental fatigue task, and immediately after completion of the assigned intervention during each experimental session.

    The theta-to-alpha power ratio was calculated from resting-state EEG recordings obtained from the Fz, Cz, Pz, O1, and O2 electrode sites by dividing theta-band power by alpha-band power. The outcome was expressed as a unitless ratio.

  3. EEG Theta/Beta Ratio

    Time frame: At baseline, immediately after the mental fatigue task, and immediately after completion of the assigned intervention during each experimental session.

    The theta-to-beta power ratio was calculated from resting-state EEG recordings obtained from the Fz, Cz, Pz, O1, and O2 electrode sites by dividing theta-band power by beta-band power. The outcome was expressed as a unitless ratio.

  4. Volleyball-Specific Agility Performance

    Time frame: Immediately after completion of each experimental protocol.

    Volleyball-specific agility performance was assessed using the Volleyball Agility Test (VAT). Performance was quantified as test completion time (seconds), with lower values indicating better agility performance.

  5. Countermovement Jump Height

    Time frame: Immediately after completion of each experimental protocol.

    Countermovement jump (CMJ) performance was assessed using the My Jump Lab application by measuring jump height in centimeters (cm), with higher values indicating better jump performance.

Secondary outcomes

  1. Countermovement Jump-Derived Mechanical and Kinematic Parameters

    Time frame: Immediately after completion of each experimental protocol.

    Countermovement jump (CMJ)-derived mechanical and kinematic parameters were obtained using the My Jump Lab application from the CMJ assessment performed at the end of each experimental protocol. Participant jump height and body mass were entered into the application's manual data-entry module, which provided flight time (ms), average velocity (m/s), take-off velocity (m/s), and impulse (kg·m/s). These parameters were analyzed as complementary derived measures of CMJ performance.

  2. Pittsburgh Sleep Quality Index (PSQI) Score

    Time frame: Baseline (before the first experimental session).

    Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), a validated self-reported questionnaire that evaluates sleep quality over the previous month. The PSQI consists of 19 self-rated items yielding a global score ranging from 0 to 21, with higher scores indicating poorer subjective sleep quality.

  3. Visual Analog Scale (VAS) Score for Perceived Nap Quality

    Time frame: Immediately after each daytime nap intervention (20-, 40-, 60-, and 90-minute nap conditions).

    Perceived nap quality was assessed using a 100-mm Visual Analog Scale (VAS). Participants rated the overall quality of their daytime nap on a horizontal line ranging from 0 mm (very poor nap quality) to 100 mm (excellent nap quality). Higher scores indicate better perceived nap quality.

Sponsors and collaborators

Lead sponsor

Inonu University

Other

Registry information

Official study title

Effects of Mental Fatigue and Different Nap Durations on Volleyball Performance and Brain Activity

Acronym: MFNAP

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Jul 14, 2026
Registry last updated
Jul 14, 2026

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

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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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