The Effects of Daytime, Nighttime, and Combined Heat Exposure on Human Health
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Daytime or Nighttime High-Temperature Exposure, Daytime and nighttime neutral temperature exposure.
- Who it may be relevant to
- Registry conditions: Metabolism Changes, Psychology Functional Behavior, Cardiovascular System, Respiratory System. Basic parameters: 18 years — 30 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- China
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
Randomized Controlled Crossover Trial on the Effects of Daytime, Nighttime, and Combined Heat Exposure on Human Health
Overview
Assess the acute effects of high-temperature exposure (including both daytime and nighttime conditions) on multiple physiological and psychological indicators, including cardiovascular, respiratory, neuropsychiatric, and metabolic functions, along with their potential mechanisms.
Detailed description
This study will be conducted in Hefei, China, as a randomized controlled crossover human exposure trial involving approximately 50 healthy young adults. The primary objective is to systematically evaluate the acute effects of heat exposure-during both daytime and nighttime-on multiple physiological and psychological domains, including cardiovascular, respiratory, neurocognitive, and metabolic functions, and to explore the underlying biological mechanisms.
A randomized crossover design will be employed, comprising three exposure phases: nighttime heat exposure, daytime heat exposure, and combined day-night heat exposure. Each participant will undergo repeated exposures under different temperature conditions, with a washout period of at least three days between sessions to minimize carryover effects.
During the nighttime exposure phase, participants will be randomly assigned to one of two sequences. Group A will first be exposed to a nighttime heat condition at 30°C from 23:00 to 07:00 (8 hours, covering habitual sleep time), followed by exposure to a thermoneutral condition at 26°C after the washout period. Group B will follow the reverse sequence.
In the daytime exposure phase, participants will again be randomized in a crossover manner. Group A will first undergo exposure to a daytime heat condition at 32°C from 09:00 to 17:00 (8 hours, approximating a typical working day), followed by exposure to a 26°C thermoneutral condition after washout. Group B will receive the reverse sequence.
In the combined day-night exposure phase, a continuous heat exposure scenario will be simulated. Group A will first be exposed to both daytime heat (32°C, 09:00-17:00) and nighttime heat (30°C, 23:00-07:00), followed by a thermoneutral condition (26°C throughout the day and night) after washout. Group B will undergo the reverse order.
Throughout each exposure session, participants will remain in a resting state to minimize the confounding effects of physical activity. Health assessments will be conducted before exposure (within 1 hour prior), during exposure, and after exposure (within 2 hours post-exposure). These assessments will include, but are not limited to, ambulatory electrocardiogram (Holter) monitoring, blood pressure measurements, spirometry, cognitive function tests, psychological questionnaires, and collection of biological samples such as blood and urine. This comprehensive evaluation will enable characterization of the acute physiological responses to heat exposure and provide insights into potential mechanistic pathways.
Interventions
- Other Daytime or Nighttime High-Temperature Exposure
Daytime Exposure Phase: The exposure group will be exposed to high temperature (32#) in a chamber for about 8 hours, resting during the whole periods Nighttime Exposure Phase: The exposure group will be exposed to high temperature (30#) in a chamber for about 8 hours, resting during the whole periods Day-Night Combined Exposure Phase: The exposure group will be exposed continuously to high temperatures during the day and night - Other Daytime and nighttime neutral temperature exposure
Daytime Exposure Phase: The control group will be exposed to neutraltemperature (26#) in a chamber for about 8 hours, resting during the whole periods Nighttime Exposure Phase: The control group will be exposed to neutral temperature (26#) in a chamber for about 8 hours, resting during the whole periods Day-Night Combined Exposure Phase: The control group will be exposed continuously to neutraltemperatures during the day and night
Primary outcome measures
- Heart Rate Variability [Time frame: Volunteers will be asked to wear smart band for 24 hours from 6:00 A.M. at the day of intervention to 6:00 A.M. at the next day.]
- Systolic and Diastolic Blood Pressure [Time frame: Blood pressure will be examined before exposure and immediately (within 10 mins) after the exposure session]
- Forced Expiratory Volume in 1 Second [Time frame: Lung function will be examined before exposure and half an hour after the exposure session]
- Forced Vital Capacity [Time frame: Lung function will be examined before exposure and half an hour after the exposure session]
- Interleukin-6 [Time frame: Blood will be collected 1 hour before and after the exposure session]
- C-reactive Protein [Time frame: Blood will be collected 1 hour before and after the exposure session]
- F2-Isoprostanes [Time frame: Blood will be collected 1 hour before and after the exposure session]
- Superoxide Dismutase [Time frame: Blood will be collected 1 hour before and after the exposure session]
- Serum Creatinine [Time frame: Blood will be collected 1 hour before and after the exposure session]
- Urinary Neutrophil Gelatinase-Associated Lipocalin [Time frame: Urine will be collected 1 hour before and after the exposure session]
Secondary outcome measures (7)
- Heart Rate [Time frame: Volunteers will be asked to wear smart band for 24 hours from 6:00 A.M. at the day of intervention to 6:00 A.M. at the next day.]
- Peak Expiratory Flow [Time frame: Lung function will be examined before exposure and half an hour after the exposure session]
- Tumor Necrosis Factor-alpha [Time frame: Blood will be collected 1 hour before and after the exposure session]
- Monocyte Chemoattractant Protein-1 [Time frame: Blood will be collected 1 hour before and after the exposure session]
- Glutathione [Time frame: Blood will be collected 1 hour before and after the exposure session]
- Blood Urea Nitrogen [Time frame: Blood will be collected 1 hour before and after the exposure session]
- Perceived Stress Scale [Time frame: Scale assessments will be conducted within one hour before and after exposure.]
Eligibility criteria
Inclusion criteria
- Age 18-30;
- In good health, with no history of cardiovascular disease, respiratory disease, diabetes, endocrine disorders, neurological or psychiatric conditions;
- No smoking or alcohol addiction, no history of substance abuse;
- No prior history of particular sensitivity to high-temperature environments.
Exclusion criteria
- Individuals who have experienced fever, colds, infectious diseases, or significant physical trauma within two weeks prior to the high-temperature test;
- Individuals currently using medications that may affect psychological, cognitive, cardiovascular, or respiratory functions;
- Pregnant women and lactating females;
- Participants shall not be scheduled to participate during menstruation;
- Individuals with a history of fainting or severe discomfort caused by high temperatures.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Crossover
- Masking
- Single blind
- Primary purpose
- Treatment
Study locations
China · 1 center
- Anhui Medical University — Hefei
Identifiers
NCT: NCT07501923 · 81250681