Acute Sleep Deprivation on Whole-body Heat Exchange During Exercise-heat Stress in Young and Older Men

NCT05838014 | Completed

• 1 other identifier: HEPRU-2023-01
• Study Type: interventional
• Target: 21
• Locations: 1 country
• Sites: 1

Brief Summary

Sleep deprivation has long been thought to modulate thermoregulatory function. Seminal work on sleep deprivation and thermoregulation has demonstrated that sleep-deprived individuals experience greater elevations in core temperature during exercise-heat stress due to reductions in the activation of local heat loss responses of cutaneous vasodilation and sweating. However, it remains unclear 1) if reductions in local heat loss responses would compromise whole-body heat loss (evaporative + dry heat exchange) and 2) if differences exist, are they dependent on the heat load generated by exercise (increases in metabolic rate augments the rate that heat must be dissipated by the body). Further, much of the understanding of the effects of sleep deprivation on thermoregulation has been limited to assessments in young adults. Studies show that aging is associated with reduction in cutaneous vasodilation and sweating that compromise whole-body heat loss exacerbating body heat storage during moderate- and especially more vigorous-intensity exercise in the heat. However, it remains unclear if sleep deprivation may worsen this response in older adults. The purpose of this study is therefore to evaluate the effects of sleep-deprivation on whole-body total heat loss during light, moderate, and vigorous exercise-heat stress and to assess if aging may mediate this response. To achieve this objective, direct calorimetry will be employed to measure whole-body total heat loss in young (18-30 years) and older (50-65 years) men during exercise at increasing, fixed rates of metabolic heat production of 150 (light), 200 (moderate), and 250 W/m2 (vigorous) in dry heat (40°C, \~15% relative humidity) with and without 24 hours of sleep deprivation.

Conditions

Thermoregulation; Sleep Disturbance; Heat Exchange; Aging; Exercise

Keywords

Heat stress; Sleep; Aging; Heat dissipation; Physical activity

Outcome Measures

Primary Outcomes (2)

• Evaporative heat loss

  Evaporative heat loss as assessed using a direct air calorimeter

  End of each exercise bout (average of last 5 minutes)

• Whole-body heat loss

  Net heat loss (dry plus/minus evaporative heat exchange) as assessed using a direct air calorimeter

  End of each exercise bout (average of last 5 minutes)

Secondary Outcomes (15)

• Dry heat loss

  End of each exercise bout (average of last 5 minutes)

• Body heat storage

  Each 30 minute exercise bout and sum of all three exercise bouts

• Core temperature

  End of each exercise bout (average of last 5 minutes)

• Change in core temperature

  End of each exercise bout (average of last 5 minutes)

• Heart rate

  End of each exercise bout (average of last 5 minutes)

Study Arms (2)

Normal sleep

ACTIVE COMPARATOR

Participants will complete three 30-minute bouts of semi-recumbent cycling at incrementally increasing fixed metabolic heat loads (150, 200 and 250 W/m2) in a hot, dry condition (40°C, 15% relative humidity). Each exercise bout will be separated by a 15 minute period of rest, with the final recovery 1 hour in duration. Exercise will commence between the hours of 7 AM and 9 AM following a period of normal sleep (\~8 hours) (Control condition).

Other: Normal sleep

Sleep deprivation

EXPERIMENTAL

Participants will complete three 30-minute bouts of semi-recumbent cycling at incrementally increasing fixed metabolic heat loads (150, 200 and 250 W/m2) in a hot, dry condition (40°C, 15% relative humidity). Each exercise bout will be separated by a 15 minute period of rest, with the final recovery 1 hour in duration. Exercise will commence between the hours of 7 AM and 9 AM following a period of 24 hour of sleep deprivation (Sleep deprivation condition).

Other: Sleep deprivation

Interventions

Sleep deprivation OTHER

Participants will undertake a period of 24 hours of total sleep deprivation prior to completing exercise

Sleep deprivation

Normal sleep OTHER

Participants will undertake \~8 hours of normal sleep prior to completing exercise

Normal sleep

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• healthy young (18-30 years) and older males (50-65 years)
• non-smoking
• English or French speaking
• ability to provide informed consent

You may not qualify if:

• presence of chronic diseases (e.g., hypertension, diabetes)
• acute illness (e.g., flu, COVID-19)
• physical restriction limiting physical activity (e.g., severe arthritis, etc.)
• use of medication judged by the patient or investigators to make participation in this study inadvisable
• engaged in regular endurance training

Sponsors & Collaborators

• University of Ottawa: lead

Study Sites (1)

University of Ottawa

Ottawa, Ontario, K1N6N5, Canada

Location

Related Publications (1)

• Koetje NJ, Kirby NV, O'Connor FK, Richards BJ, Janetos KT, Ioannou LG, Kenny GP. Effect of 24-h Sleep Deprivation on Whole-Body Heat Loss in Older Males during Exercise in the Heat. Med Sci Sports Exerc. 2025 Dec 1;57(12):2715-2723. doi: 10.1249/MSS.0000000000003812. Epub 2025 Jul 7.

  PMID: 40623158 DERIVED

MeSH Terms

Conditions

Parasomnias; Motor Activity; Heat Stress Disorders

Condition Hierarchy (Ancestors)

Sleep Wake Disorders; Nervous System Diseases; Mental Disorders; Behavior; Wounds and Injuries

Study Design

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

Model Details: Each participant will complete two exercise trials in a hot, dry environment (40°C, 15% relative humidity) where they will perform three 30 min bouts of exercise at incrementally increasing metabolic heat loads (each separated by a 15-min rest) following a period of either (i) normal sleep or (ii) 24 h of sleep deprivation.

Study Record Dates

• First Submitted: March 30, 2023
• First Posted: May 1, 2023
• Study Start: December 1, 2022
• Primary Completion: June 29, 2023
• Study Completion: June 29, 2023
• Last Updated: July 15, 2024

Record last verified: 2024-07

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ANALYTIC CODE
• Time Frame: Following publication of the main study (report(s)
• Access Criteria: Approved analysis plan and signed access agreement

Locations

CA (1)