Skip to main content
OpenTrials
Completed

NCT Number: NCT07758166

The First-Night Effect and Sex Differences in Strength and Muscular Endurance Performance

Introduction: The first-night effect, characterized by disturbed sleep in an unfamiliar environment, may impair next-day physical performance. However, whether this response differs between men and women remains unclear. This study investigated sex differences in the effects of sleeping in an unfamiliar environment on strength and muscular endurance in resistance-trained individuals.

Methods: Thirty-two resistance-trained participants (16 women, 16 men; 23 ± 4 years) completed a randomized, counterbalanced crossover study involving two conditions: sleeping for 8 h at home or in the laboratory. The following morning, participants performed bench press and back squat strength tests across 25-90%1RM, followed by muscular endurance tests to failure at 65%1RM.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Sleep

Age range

18 year–40 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Facultad de Medicina y Ciencias de la Salud. Universidad de Alcalá

Alcalá de Henares, Madrid, 28805, Spain

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Age between 18 and 35 years.• Body Mass Index (BMI) < 25 kg/m².
  • Resistance-trained individuals (more than 2 years of structured training).
  • Healthy men and women without neurological, cardiometabolic, immunological, or physical conditions that prevent them from exercising.
  • Participants must be able to perform the tests described in the following section.

Exclusion criteria

  • History of neuromuscular diseases, heart disease, or conditions that may affect liver or muscle metabolism.
  • Use of drugs, stimulants, or sports supplements that could interfere with the dietary supplement used in the study.
  • Sedentary habits (less than 150 minutes/week of moderate exercise).• Having undergone prolonged periods of physical inactivity in the 6 months prior to the study.
  • Engaging in strenuous exercise within 48 hours prior to the tests.• Failure to replicate the same food intake on both experimental days.
  • Consumption of caffeine or any other stimulant the day before the tests.

Treatment and study plan

First-Night Effect at the laboratory

Behavioral

Participants sleep 8h at the laboratory

first-night effect (at home)

Behavioral

Participants sleep 8h at home

Primary outcomes

  1. Mean velocity at different %1RM

    Time frame: Through study completion, an average of 3 weeks

    Mean velocity at different %1RM (25%, 50%, 75%, 90%)

  2. Number of repetitions performed during 1 set at 65%1RM until task failure

    Time frame: Through study completion, an average of 3 weeks

    In bench press and back squat exercises

  3. Bar velocity deplacement performed in 1 set at 65%1RM until task failure

    Time frame: Through study completion, an average of 3 weeks

    In bench press and back squat exercises

  4. Handgrip and isometric mid-thigh pull tests

    Time frame: Through study completion, an average of 3 week

    N generated

  5. Vertical Jump test (CMJ)

    Time frame: Through study completion, an average of 3 week

    cm of Height and W/kg generate during a CMJ

Secondary outcomes

  1. Mood state (tension, depression, anger, vigor, fatigue and confusion)

    Time frame: Through study completion, an average of 3 weeks

    Participants graded a set of 29 items related to the mood on a Likert scale from 0 (not at all) to 4 (extremely) in reply to the question;How do you feel at this moment?; to assess six scales: tension, depression, anger, vigor, fatigue and confusion.

Sponsors and collaborators

Lead sponsor

University of Alcala

Other

Registry information

Official study title

The First-Night Effect: Sex Differences in the Impact of Unfamiliar Sleeping Environment on Strength and Muscular Endurance Performance in Resistance-trained Participants

Important dates

Study start
2024
Primary completion
2025
Study completion
2026
First posted
Aug 11, 2026
Registry last updated
Aug 11, 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.

Related clinical trials

Published trials that share one or more normalized conditions with this study.