The Effects of Daytime, Nighttime, and Combined Heat Exposure on Human Health

Официальное название

Randomized Controlled Crossover Trial on the Effects of Daytime, Nighttime, and Combined Heat Exposure on Human Health

Обзор

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.

Подробное описание

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.

Вмешательства

• Другое 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
• Другое 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

Первичные конечные точки

• Heart Rate Variability [Срок оценки: 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 [Срок оценки: Blood pressure will be examined before exposure and immediately (within 10 mins) after the exposure session]
• Forced Expiratory Volume in 1 Second [Срок оценки: Lung function will be examined before exposure and half an hour after the exposure session]
• Forced Vital Capacity [Срок оценки: Lung function will be examined before exposure and half an hour after the exposure session]
• Interleukin-6 [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• C-reactive Protein [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• F2-Isoprostanes [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• Superoxide Dismutase [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• Serum Creatinine [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• Urinary Neutrophil Gelatinase-Associated Lipocalin [Срок оценки: Urine will be collected 1 hour before and after the exposure session]

Вторичные конечные точки (7)

• Heart Rate [Срок оценки: 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 [Срок оценки: Lung function will be examined before exposure and half an hour after the exposure session]
• Tumor Necrosis Factor-alpha [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• Monocyte Chemoattractant Protein-1 [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• Glutathione [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• Blood Urea Nitrogen [Срок оценки: Blood will be collected 1 hour before and after the exposure session]
• Perceived Stress Scale [Срок оценки: Scale assessments will be conducted within one hour before and after exposure.]

Критерии участия

Критерии включения

• 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.

Критерии исключения

• 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.

Критерии приведены из реестра в оригинале (на английском). Окончательную оценку соответствия проводит исследовательский центр.

Здоровые добровольцы: Да

Дизайн исследования

Распределение

Рандомизированное

Модель

Перекрёстный дизайн

Маскирование

Простое слепое

Основная цель

Лечение

Центры проведения

Китай · 1 центр

• Anhui Medical University — Хэфэй

Идентификаторы

NCT: NCT07501923 · 81250681

Первоисточники (государственные реестры)

• ClinicalTrials.gov (NIH, США)

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