What Temperature Your Bedroom Should Be in Summer. Medical Tips for a Good Night's Sleep During a Heatwave

Hot summer nights don't just cause discomfort — they can seriously affect the quality of your sleep. Dr. Andreea Mihaela Popa, a pulmonologist, explained to Digi24.ro what happens to the body during a heatwave, what temperature a bedroom should be, and which habits can help you sleep better.

Why heat affects our sleep

According to the doctor, before falling asleep, the body naturally lowers its core temperature — a process essential for sleep to set in. When the bedroom is too warm, this temperature drop becomes difficult, delaying the onset of sleep and reducing the quality of rest.

On sweltering nights, sleep becomes shallow and frequent waking occurs. The stages most affected are deep sleep (N3) and REM sleep, which are essential for physical recovery, memory, and cognitive and emotional functioning. As a result, even if the number of hours slept seems sufficient, the quality of rest is poor. The following day may bring fatigue, drowsiness, difficulty concentrating, irritability, and reduced physical and mental performance.

The doctor notes that, according to various studies and the recommendations of the American Academy of Sleep Medicine (AASM) and the European Sleep Research Society (ESRS), the temperature of the sleeping environment is one of the most important factors influencing the quality of rest.

Nocturnal thermal discomfort affects everyone, but the most vulnerable are infants and young children, elderly people, pregnant women, and patients with cardiovascular, respiratory, metabolic, or neurological conditions. In people with asthma or COPD, high temperatures can worsen night-time symptoms and negatively impact the underlying condition.

The ideal bedroom temperature

For most healthy adults, the optimal bedroom temperature is between 18 and 20 degrees Celsius, although thermal comfort varies depending on age, health status, and personal preference.

How to keep the bedroom cool

• Ventilate rooms in the early morning and late evening, when it is cooler outside
• Use blackout curtains or blinds to limit heat penetration during the day
• Reduce indoor heat sources, such as electronic devices left on standby or bright lighting

Air conditioning or a fan at night?

Both can be used, but correctly. Air conditioning should be set at approximately 6–8°C below the outside temperature, avoiding excessively large differences. The airflow should not be directed straight at the sleeping person, and the unit's filters should be cleaned regularly to maintain good air quality.

A fan creates a sensation of coolness, but should not be pointed directly at the body throughout the entire night. Used responsibly, both options can improve thermal comfort without any negative effects on health.

Useful bedtime habits

Staying hydrated throughout the day is important, but drinking large quantities of fluids immediately before bed can cause night-time waking. A lukewarm shower 30–60 minutes before sleep helps the body cool down gradually and promotes relaxation.

In the evening, it is advisable to avoid alcohol, coffee, energy drinks, and nicotine, as these delay the onset of sleep. A light dinner, eaten at least two to three hours before bedtime, allows digestion to take place without placing unnecessary strain on the body.

Loose-fitting clothing made from natural fibres (cotton, linen) and breathable bed linen contribute to comfort. Limiting the use of phones, tablets, or television at least one hour before bed supports melatonin secretion — the hormone that regulates the sleep–wake cycle. Strenuous exercise should be avoided in the evening, as intense physical effort raises body temperature and makes it harder to fall asleep, particularly during a heatwave.

When sleep deprivation becomes a health concern

If sleep deprivation persists for several weeks, it is no longer simply discomfort caused by the heat — it may signal an underlying health issue requiring medical assessment. Excessive daytime sleepiness, confusion, breathing difficulties, palpitations, signs of dehydration, or symptoms of heatstroke are all reasons to seek medical advice as soon as possible.