How cool should you keep your bedroom at night?

Maintaining a bedroom temperature of 24°C overnight can reduce stress responses and heart rate variability in older adults, new research from Griffith University has suggested.

The study, which examined how increasing nighttime bedroom temperatures affected heart rate and stress responses in people aged 65 years and over, was published in academic journal BMC Medicine and titled ‘Effect of nighttime bedroom temperature on heart rate variability in older adults.’

“For individuals aged 65 years and over, maintaining overnight bedroom temperatures at 24°C reduced the likelihood of experiencing heightened stress responses during sleep,” Dr O’Connor said.

The research focused on how heat exposure influences the cardiovascular system during sleep, a period critical for physiological recovery.

“When the human body is exposed to heat, its normal physiological response is to increase the heart rate,” Dr O’Connor wrote.

“The heart is working harder to try and circulate blood to the skin surface for cooling.

“However, when the heart works harder and for longer, it creates stress and limits our capacity to recover from the previous day’s heat exposure.”

Participants in the study wore fitness activity trackers on their non-dominant wrist to measure heart rate data, while temperature sensors installed in bedrooms monitored overnight conditions. Data was collected over the course of the 2025/26 Australian summer, providing real-world evidence of how warmer sleeping environments influence heart rate variability and stress responses.

According to the researchers, the findings have broader implications as climate change increases the frequency of hot nights.

“Climate change is increasing the frequency of hot nights, which may independently contribute to cardiovascular morbidity and mortality by impairing sleep and autonomic recovery,” Dr O’Connor said.

“While there are guidelines for maximum daytime indoor temperature being 26°C, there are no equivalent recommendations for nighttime conditions.”

IMPORTANT LEGAL INFO This article is of a general nature and FYI only, because it doesn’t take into account your personal health requirements or existing medical conditions. That means it’s not personalised health advice and shouldn’t be relied upon as if it is. Before making a health-related decision, you should work out if the info is appropriate for your situation and get professional medical advice.