Heat Disrupts Sleep: Doctor Explains the Dangers of Tropical Nights and How to Cool Your Bedroom

Czechia is bracing for yet another extremely warm night, with temperatures in some regions not expected to drop below 20 degrees Celsius. General practitioner Cyril Mucha spoke in an interview about how to maintain sleep quality in such conditions and what health risks the heat poses.

According to him, the ideal sleeping temperature is around 18 degrees Celsius, and this holds true for most people regardless of age. However, elderly people, those with chronic illnesses, and young children have a harder time compensating for deviations from this norm.

There's no clear-cut "critical" temperature — much depends on how well-conditioned a person's body is and their overall physical state. But once temperatures approach or exceed 30 degrees, the body can no longer cool itself effectively without heavy sweating, which becomes a real problem during sleep.

The doctor explained that the body has a so-called "core" — the area around the chest containing the lungs and heart. These organs need a stable temperature the most in order to function properly. When the body's temperature-regulation mechanisms fail to keep up, overheating sets in, and in extreme cases this can lead to collapse, cardiac arrhythmia, and even death.

At night, the heart and other organs normally operate in a low-strain mode, and blood pressure ideally drops by at least 10%. If the heat forces the body to activate compensatory mechanisms instead, rest becomes less restorative — and a person may wake up more exhausted than when they went to bed.

For a healthy young person, hot nights usually aren't dangerous — sleep may simply be less comfortable, without posing a serious threat. The at-risk groups, however, include children under two and adults over 65–70, as well as people who are obese, have thyroid conditions (especially hyperthyroidism), or suffer from heart disease, including those who have had a heart attack.

According to the doctor, short-term nighttime overheating typically doesn't cause lasting harm — if temperatures drop the following day, the body recovers. That said, it's important to maintain proper hydration, since failing to do so can lead to kidney failure.

Among his practical tips, the doctor emphasized darkening the bedroom and airing it out only in the morning and evening — not at night, when hot air is still pouring in from outside. Curtains and blinds should be kept as close to the window as possible, and can even be dampened with water before bed. It's also worth avoiding heavy meals in the evening, since digestion generates additional body heat.

It's best to sleep in light, ideally cotton clothing and avoid synthetic fabrics. For a cooling effect, a bedsheet can be placed in the fridge or freezer beforehand. Fans and air conditioners are fine to use, but the difference between indoor and outdoor temperatures shouldn't exceed five degrees — otherwise there's a risk of catching a cold, developing a dry cough, or getting a sore throat due to the sharp temperature change. Ceiling fans, which simply circulate air, are considered a safer option than direct exposure to air-conditioning airflow.

The doctor also had a word of caution for those planning holidays in hot countries: travel itself puts significant strain on the body, so it's worth soberly weighing whether the risk is justified before setting off. Hotels in hot countries typically come with air conditioning as standard, which can actually make sleep more comfortable than at home — but temperature swings remain a potential hazard.

The doctor admitted that during the hot season, he sees patients every day complaining of insomnia, irritability, and flare-ups of chronic conditions caused by lack of sleep. His first recommendation is always preventive measures to improve sleep, and in certain cases, a short course of sleeping pills — although he personally says he isn't an advocate of such medication.

Around Prague, based on reporting by seznamzpravy.cz