"Turning Off the Air Conditioner Can Be Dangerous"...Heart Strain Increases When Bedroom Temperature Exceeds 24 Degrees Celsius

Australian Study Observes Adults Over 65
Heart Strain Increases When Bedroom Temperature Exceeds 24 Degrees Celsius

A study has found that if the bedroom temperature exceeds 24 degrees Celsius during summer, it can place a greater strain on the heart during sleep.

According to a paper published in the international journal BMC Medicine on July 2, researchers at Griffith University in Australia studied the relationship between summer bedroom temperature and heart function in 47 adults aged 65 and older (average age 72) living in Queensland from December 2024 through March of the following year. The study participants wore wearable devices to measure their heart rates and heart rate variability (HRV) during sleep, and temperature sensors were installed in their bedrooms. The researchers collected a total of 14,179 hours of sleep data. The results showed that when the bedroom temperature exceeded 24 degrees Celsius, there was a tendency for cardiac recovery to decline.

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The risk of decreased heart rate variability rose by about 40% when the bedroom temperature was between 24 and 26 degrees Celsius, doubled when it was 26 to 28 degrees Celsius, and tripled when it exceeded 28 degrees Celsius. Regarding these findings, the research team explained, "When people fall asleep, their core body temperature drops and they enter deep sleep. However, if the bedroom is excessively warm, this process is disrupted, and the heart must pump more blood to lower body temperature, preventing proper rest throughout the night."

However, there are limitations to this study. It was not confirmed whether the participants used cooling devices such as fans or air conditioners, and the sample size was relatively small at 47 people. Furthermore, as an observational study, it is difficult to definitively conclude that temperature itself is the direct cause of changes in heart rate variability.

On the other hand, excessive use of air conditioning can also put a burden on the heart. According to statistics from the Health Insurance Review and Assessment Service, cases of acute myocardial infarction occurred more frequently in summer than in winter between December 2020 and August 2025. Over the five-year period, the number of patients in summer totaled 502,086, about 13,500 more than the 488,506 cases recorded in winter. Approximately 80% of all patients were men, with the highest proportion in their 60s. Acute myocardial infarction is a serious emergency condition in which a blood clot suddenly blocks the coronary arteries that supply blood to the heart muscle, causing part of the heart muscle to die.

When someone is exposed to extreme heat and then enters an air-conditioned indoor space, blood vessels that had expanded to release heat suddenly constrict, placing significant stress on the heart. If atherosclerotic plaques that have built up on the vessel wall rupture as a result, this can lead to acute myocardial infarction, so extra caution is needed.

This content was produced with the assistance of AI translation services.