Bajar la temperatura del dormitorio reduce el riesgo de crisis cardiovasculares

Author: Gao Jie

Title: Lowering Bedroom Temperature Reduces the Risk of Cardiovascular Crises

In the context of global warming, extreme heat events are becoming increasingly frequent. Nighttime, which should be a time for the body to relax and regain energy, is silently threatened by the continuous rise in bedroom temperatures, putting the cardiovascular health of the elderly at risk.

Recently, a new study published in "BMC Medicine" has revealed the impact of bedroom temperature at night on heart rate and heart rate variability in older adults, providing a fundamental basis for establishing standards for nighttime indoor temperatures.

Source: screenshots from the study.

For individuals aged 65 and older, maintaining the bedroom temperature at night at 24°C can reduce the likelihood of intensified stress reactions during sleep, says Dr. Fergus O'Connor from the School of Health, Sport and Social Work at Griffith University.

A research team asserts that the World Health Organization has only established a maximum temperature standard for indoor settings during the day (26°C), but nighttime bedroom temperature, a key factor closely related to sleep quality and body recovery, has long been overlooked. Therefore, they have focused their attention on how increased temperatures in bedrooms at night affect heart rate and stress levels in the elderly, aiming to provide scientific support for ensuring the nighttime health of older adults.

How can intense heat silently damage the cardiovascular system of older adults? Dr. O'Connor thoroughly explains the heavy burden that intense heat places on the cardiovascular system of the elderly, revealing the central mechanism by which high nighttime temperatures affect the health of this age group. He points out that due to the gradual decline of physical functions in the elderly, their ability to regulate body temperature and cardiovascular reserve is much lower than in younger individuals. At night, when metabolism slows down and the autonomic nervous system is in a state of regulation and repair, heat stimulation can impact the body in a more subtle and lasting manner.

When the body is exposed to a hot environment, the normal physiological response is to increase heart rate; the heart has to work harder to pump blood toward the skin surface and allow sweat evaporation as a way to dissipate heat. This process, which seems ordinary, actually hides a crisis: for the elderly, the functioning of the heart under heavy load for prolonged periods can lead not only to organ fatigue and a constant increase in heart rate but also to an intensification of the physiological stress response, limiting the body's ability to recover from the thermal exposure of the previous day. In the long term, this can induce a series of cardiovascular problems.

The study on the fundamental relationship between temperature and health will be conducted from December 2024 to March 2025 during the Australian summer and will monitor 47 elderly individuals aged 65 or older residing in the southeastern Queensland community.

To obtain the most accurate and precise data, the research team employed a dual monitoring method: participants wore a physical activity tracker on the non-dominant wrist, continuously recording heart rate and related heart rate variability data during sleep; simultaneously, a temperature sensor installed in the bedroom continuously monitored nighttime environmental temperature at 10-minute intervals throughout the study period. In total, 14,179 hours of effective nighttime monitoring were collected, and the average nighttime bedroom temperature during the monitoring period was 25.9 °C.

The study classifies the nighttime bedroom temperature into four gradations: below 24°C, 24 to 26°C, 26 to 28°C, and 28 to 32°C, taking the temperature below 24°C as the reference group.

The analysis reveals that as temperature increases, so does the risk to cardiovascular health in older adults. In particular, at temperatures of 24-26 °C, the probability of elderly individuals experiencing a clinically significant decrease in lnRMSSD (a key indicator of heart rate variability) increases by 1.4 times; between 26-28 °C, this probability rises to 2.0 times; and between 28-32 °C, it reaches up to 2.9 times. Furthermore, higher temperatures are associated with a decrease in lnHF and lnLF (high and low-frequency heart rate variability), an increase in ln(LF:HF) (the ratio of low to high frequency), and an increase in heart rate.

These data clearly indicate that the increase in nighttime temperature in the bedroom directly affects heart rate and stress response during sleep, causing damage to the autonomic nervous system and cardiovascular system of older adults. Notably, this effect does not show differences regardless of whether participants were taking medications related to heat sensitivity, suggesting that the risk is universal.

With the worsening of climate change, the frequency of hot nights is increasing. Dr. O'Connor notes that this could independently increase the incidence and mortality from cardiovascular diseases.

This study not only provides for the first time direct evidence of the relationship between nighttime temperature in real-life situations and the cardiovascular physiological state of the elderly, clarifying the critical protective threshold of 24°C, but also fills a gap in the research. Additionally, it indicates a direction for protecting the health of older adults in the summer: keeping the bedroom temperature below 24°C is essential for preserving the stability of autonomic nervous system function and reducing cardiovascular physiological stress.

Moreover, the research also provides supporting data for the formulation of public health policies. In the future, the nighttime indoor temperature threshold should be incorporated into the health protection framework against high temperatures. Through indoor temperature monitoring and early warning systems for at-risk populations, the aim is to mitigate the negative impact of high nighttime temperatures on the health of the elderly.