Researchers explore how to beat heat for better sleep

Free Malaysia Today

17-05-2025

As neurons regulating temperature and sleep in the brain are highly interconnected, lowering the body's internal thermostat is key to improving sleep quality. (Envato Elements pic)
PARIS : Sleep quality is being harmed by hotter temperatures caused by climate change, and scientists say we need to learn how to adapt.
The human brain is very sensitive to heat, with higher temperatures raising the body's central thermostat and activating stress systems.
Experts are increasingly exploring mechanisms that can help the body adapt to rising temperatures affecting our sleep and leading to health complications.
'Rising temperatures induced by climate change and urbanisation pose a planetary threat to human sleep and, therefore, to health, performance and wellbeing,' says a review of scientific literature published last year in the journal Sleep Medicine.
Meanwhile, a 2022 study published in the journal One Earth highlighted that humans lost an average of 44 hours of sleep a year during the first two decades of the 21st century compared to earlier periods, linking the data to rising temperatures.
The intensification of global warming could lead to an annual loss of 50-58 hours of sleep per person by 2099, according to research led by Kelton Minor from the University of Copenhagen, based on data gathered from more than 47,000 individuals in 68 countries.
'Interventional studies and field experiments are now urgently needed to safeguard the essential restorative role of sleep in a hotter world,' Minor and colleagues said.
As neurons regulating temperature and sleep in the brain are highly interconnected, lowering the body's internal thermostat is key to improving sleep quality. But adapting to heat comes at a cost to the body, according to researcher Fabien Sauvet from Paris Cite University.
'We sweat more and faster, and require additional hydration. So, during heatwaves, the most important thing is to adapt our behaviour' with regard to activities, schedules and clothing, Sauvet said.
Still, humans can 'tolerate higher temperatures than commonly thought', he added, pointing to several studies showing that good sleep quality can be achieved with a room temperature of up to 28°C.
An excessive lack of sleep can disrupt the body's recovery, leading to drowsiness, fatigue, and a higher risk of accidents at the workplace or on the road. (Envato Elements pic)
Challenging 'the false belief that the bedroom must be at 18-20°C', he added that sleeping in light clothing such as a t-shirt and shorts, and with a simple sheet as well as good ventilation, could help dealing with a few more degrees.
'If we always sleep with air conditioning, we will never acclimatise,' he noted.
Fight 'sleep enemies'
Armelle Rancillac, a neuroscientist at the Centre for Interdisciplinary Research in Biology, said anything beyond 28°C 'becomes much more complicated'.
An excessive lack of sleep is known to disrupt the body's recovery. In the short term, this could lead to drowsiness, fatigue, and a higher risk of accidents at the workplace or on the road.
In the long run, it can create a harmful sleep 'debt', impacting our metabolism and increasing the risk of weight gain, diabetes, cardiovascular diseases, and even neurodegenerative diseases like Alzheimer's, Rancillac outlined.
A sleep deficit can also reduce stress resistance and have a negative impact on mental health.
To sleep better in a hotter environment, Rancillac stressed that there is a need to 'eliminate or at least pay attention to sleep enemies'.
Before bedtime, it is recommended to take a cool shower (but not an icy one), reduce stimulants like coffee, and limit alcohol, which facilitates falling asleep but slightly raises the internal body temperature.
Avoid hot tubs after a workout, opting instead for outdoor temperatures or a cold bath, Sauvet said.
Napping during the hottest hours of the day have also been proven to mitigate the impacts of a sleep deficit. Short naps – '30 to 40 minutes, and before 2pm' – are ideal, so as not to interfere with a good night's sleep, according to the researcher.