Cardiovascular System, Metabolism Changes, Psychology Functional Behavior, Respiratory System
Conditions
Brief summary
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
OTHERDaytime 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
OTHERDaytime 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
Sponsors
Jian Cheng
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 30 Years
Healthy volunteers
Yes
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Heart Rate Variability | 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. | Smart Band will be conducted during each exposure session. Time-domain and frequency-domain HRV indices (e.g., SDNN, RMSSD, LF, HF) will be derived to assess autonomic nervous system regulation. |
| Systolic and Diastolic Blood Pressure | Blood pressure will be examined before exposure and immediately (within 10 mins) after the exposure session | Blood pressure will be measured using an automated sphygmomanometer under standardized resting conditions. Both systolic and diastolic values will be recorded. |
| Forced Expiratory Volume in 1 Second | Lung function will be examined before exposure and half an hour after the exposure session | Pulmonary function will be assessed using spirometry according to standardized protocols. FEV1 will be recorded as a measure of airway function. |
| Forced Vital Capacity | Lung function will be examined before exposure and half an hour after the exposure session | Forced vital capacity will be measured via spirometry to evaluate lung volume and ventilatory function. |
| Interleukin-6 | Blood will be collected 1 hour before and after the exposure session | Venous blood samples will be collected and serum IL-6 concentrations will be quantified using enzyme-linked immunosorbent assay (ELISA) to assess systemic inflammatory response. |
| C-reactive Protein | Blood will be collected 1 hour before and after the exposure session | Serum CRP levels will be measured using high-sensitivity assays as a marker of systemic inflammation. |
| F2-Isoprostanes | Blood will be collected 1 hour before and after the exposure session | Plasma or urinary F2-isoprostanes will be quantified using validated assays as a stable biomarker of lipid peroxidation and oxidative stress. |
| Superoxide Dismutase | Blood will be collected 1 hour before and after the exposure session | Serum SOD activity will be measured to evaluate antioxidant defense capacity. |
| Serum Creatinine | Blood will be collected 1 hour before and after the exposure session | Serum creatinine will be measured using standard biochemical methods to assess renal function. |
| Urinary Neutrophil Gelatinase-Associated Lipocalin | Urine will be collected 1 hour before and after the exposure session | Urinary NGAL levels will be quantified using ELISA as an early biomarker of acute kidney injury. |
| Profile of Mood States | Scale assessments will be conducted within one hour before and after exposure. | Psychological status will be assessed using the validated POMS questionnaire to evaluate mood disturbances. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Heart Rate | 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. | Heart rate will be continuously recorded during exposure using wearable devices. |
| Peak Expiratory Flow | Lung function will be examined before exposure and half an hour after the exposure session | PEF will be measured using a portable peak flow meter to assess expiratory function. |
| Tumor Necrosis Factor-alpha | Blood will be collected 1 hour before and after the exposure session | Serum TNF-α levels will be measured using ELISA. |
| Monocyte Chemoattractant Protein-1 | Blood will be collected 1 hour before and after the exposure session | Serum MCP-1 concentrations will be quantified to assess inflammatory activation. |
| Glutathione | Blood will be collected 1 hour before and after the exposure session | Reduced glutathione levels will be measured to assess antioxidant capacity. |
| Blood Urea Nitrogen | Blood will be collected 1 hour before and after the exposure session | Blood Urea Nitrogen will be measured using standard biochemical assays. |
| Perceived Stress Scale | Scale assessments will be conducted within one hour before and after exposure. | Perceived stress will be assessed using the validated Perceived Stress Scale questionnaire. |
Countries
China
Contacts
CONTACTJian Jian Cheng
Outcome results
None listed