Clinical trial NCT05838014: Acute Sleep Deprivation on Whole-body Heat Exchange During Exercise-heat Stress in Young and Older Men
Official title: The Effect of Sleep Deprivation on Whole-body Heat Loss in Young and Older Men During Exercise in Hot, Dry Conditions
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Thermoregulation
Sleep Disturbance
Heat Exchange
Aging
Exercise
Keywords: Heat stress
Sleep
Aging
Heat dissipation
Physical activity
Lead sponsor: University of Ottawa
Sponsor class: OTHER
First posted: 2023-05-01
Enrollment: 21
Sex: MALE
Minimum age (years): 18
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: 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.
Primary purpose: BASIC_SCIENCE

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.


Eligibility criteria: Inclusion Criteria:

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

Exclusion Criteria:

* 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

Primary outcomes:
measure: Evaporative heat loss
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Whole-body heat loss
timeFrame: End of each exercise bout (average of last 5 minutes)
Secondary outcomes:
measure: Dry heat loss
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Body heat storage
timeFrame: Each 30 minute exercise bout and sum of all three exercise bouts
measure: Core temperature
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Change in core temperature
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Heart rate
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Heart rate reserve
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Local sweat rate (forearm, scapula)
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Skin temperature
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Skin temperature (change)
timeFrame: End of each exercise bout (average of last 5 minutes)
measure: Thermal comfort scale
timeFrame: End of the 30 minute resting baseline period, end of each 30 minute exercise bout, end of each 15 minute rest period, and 1 hour after final exercise period.
measure: Thermal sensation
timeFrame: End of the 30 minute resting baseline period, end of each 30 minute exercise bout, end of each 15 minute rest period, and 1 hour after final exercise period.
measure: Thirst sensation
timeFrame: End of the 30 minute resting baseline period, end of each 30 minute exercise bout, end of each 15 minute rest period, and 1 hour after final exercise period.
measure: Rating of perceived exertion
timeFrame: End of the 30 minute resting baseline period, end of each 30 minute exercise bout, end of each 15 minute rest period, and 1 hour after final exercise period.
measure: Stanford sleep scale
timeFrame: End of the 30 minute resting baseline period, end of each 30 minute exercise bout, end of each 15 minute rest period, and 1 hour after final exercise period.
measure: Variables of heart rate variability
timeFrame: End of each exercise (average of last 5 minutes)
Other outcomes:
Locations:
city: Ottawa
country: Canada
facility: University of Ottawa
state: Ontario
Study officials:
References: