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

NCT07700576 | Completed

• 2 other identifiers: OB-MFNAP-2026-01TDK-2025-4002
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Mental Fatigue; Recovery; Volleyball; Sport Performance

Keywords

Mental Fatigue; Nap; Volleyball; EEG; Electroencephalography; Recovery; Agility; Countermovement Jump; Cognitive Performance; Brain Activity; Athletes

Outcome Measures

Primary Outcomes (5)

• EEG Spectral Power

  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).

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

• EEG Theta/Alpha Ratio

  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.

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

• EEG Theta/Beta Ratio

  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.

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

• Volleyball-Specific Agility Performance

  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.

  Immediately after completion of each experimental protocol.

• Countermovement Jump Height

  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.

  Immediately after completion of each experimental protocol.

Secondary Outcomes (3)

• Countermovement Jump-Derived Mechanical and Kinematic Parameters

  Immediately after completion of each experimental protocol.

• Pittsburgh Sleep Quality Index (PSQI) Score

  Baseline (before the first experimental session).

• Visual Analog Scale (VAS) Score for Perceived Nap Quality

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

Study Arms (6)

Control

ACTIVE COMPARATOR

Participants completed the control condition without mental fatigue induction or daytime nap intervention. A neutral documentary was viewed for 15 minutes. Resting-state EEG recordings, volleyball-specific agility performance, and countermovement jump performance were assessed according to the study protocol.

Other: Control Condition

Mental Fatigue

EXPERIMENTAL

Participants completed a 15-minute computerized Stroop task to induce mental fatigue. Following the mental fatigue protocol, resting-state EEG recordings, volleyball-specific agility performance, and countermovement jump performance were assessed.

Behavioral: Mental Fatigue Induction

Nap20

EXPERIMENTAL

Participants completed a 15-minute computerized Stroop task followed by a supervised 20-minute daytime nap. Resting-state EEG recordings, volleyball-specific agility performance, and countermovement jump performance were assessed after the nap intervention.

Behavioral: Mental Fatigue Induction; Behavioral: Daytime Nap 20 Minutes

Nap40

EXPERIMENTAL

Participants completed a 15-minute computerized Stroop task followed by a supervised 40-minute daytime nap. Resting-state EEG recordings, volleyball-specific agility performance, and countermovement jump performance were assessed after the nap intervention.

Behavioral: Mental Fatigue Induction; Behavioral: Daytime Nap 40 Minutes

Nap60

EXPERIMENTAL

Participants completed a 15-minute computerized Stroop task followed by a supervised 60-minute daytime nap. Resting-state EEG recordings, volleyball-specific agility performance, and countermovement jump performance were assessed after the nap intervention.

Behavioral: Mental Fatigue Induction; Behavioral: Daytime Nap 60 Minutes

Nap90

EXPERIMENTAL

Participants completed a 15-minute computerized Stroop task followed by a supervised 90-minute daytime nap. Resting-state EEG recordings, volleyball-specific agility performance, and countermovement jump performance were assessed after the nap intervention.

Behavioral: Mental Fatigue Induction; Behavioral: Daytime Nap 90 Minutes

Interventions

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.

Mental Fatigue; Nap20; Nap40; Nap60; Nap90

Control Condition OTHER

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

Control

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.

Nap20

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.

Nap40

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.

Nap60

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.

Nap90

Eligibility Criteria

• Age: 19 Years - 22 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• Inonu University: lead

Study Sites (1)

Inonu University, Faculty of Sport Sciences

Malatya, Malatya, 44280, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Mental Fatigue

Condition Hierarchy (Ancestors)

Fatigue; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Behavioral Symptoms; Behavior

Study Officials

• Ozgur EKEN, Associate Professor

  Inonu University

  STUDY CHAIR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Model Details: Randomized crossover repeated-measures design. Each participant completed all six experimental conditions in a randomized order with a 72-hour washout period between sessions.

Study Record Dates

• First Submitted: June 30, 2026
• First Posted: July 14, 2026
• Study Start: October 1, 2025
• Primary Completion: December 1, 2025
• Study Completion: December 1, 2025
• Last Updated: July 14, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)