Doctor warns of alarming health risks of sleeping with a fan on during a heatwave

Daily Mail​

30-04-2025

Sleeping with a fan on could leave you with a hacking cough, chest pain and agonising muscle aches, a doctor has warned.
According to US-based medic Dr Naheed Ali, running the cooling device all night puts 'hidden stress' on the body, including leaving the throat and airways irritated, and restricting blood flow to the muscles.
The health risks may be even more significant for those with severe allergies and asthma, as the airflow whips up particles of dust and dirt, which are then inhaled into the lungs.
'People with asthma allergies often wake with extra chest tightness after a night with the fan on,' Dr Ali said.
His warning comes as the UK is set to experience a heatwave, with temperatures predicted to reach up to 30°C in some areas of the UK by Thursday, the Met Office reports.
Many will no doubt be reaching for the devices to aid sleep, as studies show the optimum room temperature for a restful night is between 16°C and 18°C.
'The steady airflow of the fan can leave the nasal passages and throat uncomfortably dry by morning,' Dr Ali told LADbible.
The dry air irritates the airways, causing a build-up of mucus in the nose and sinuses, and phlegm in the throat.
Dr Ali said: 'A dry airway produces thicker mucus, which can trap allergens and irritants close to sensitive tissue.
'Over time, this may trigger coughing, a scratchy voice, or clogged sinuses that linger throughout the day'.
As for those with allergies: 'Tiny particles of lint, dander, and pollen stay in motion and may reach deeper into the airways while you sleep.'
Sleeping with a fan on could also trigger muscle problems.
Dr Ali said: 'Cool air against muscles and joints for seven or eight hours can cause a subtle drop in tissue temperature.
'The chilled muscles tighten as a natural defense, and that tension may persist until a warm shower or gentle stretching restores normal blood flow.'
However, Dr Ali said, you don't necessarily have to turn the fan off to avoid all side effects.
He suggested using a timer to limit running time, washing bedding more regularly to reduce the amount of airborne dust, and facing the fan away from the bed.
'If a fan is the only way to keep the room comfortable, place it on a timer that shuts off after the first sleep cycle of ninety minutes.
'Direct the airflow toward an opposite wall rather than straight at the bed, and keep a glass of water at the bedside to sip if the mouth feels dry.'
He added: 'These small adjustments let the fan cool the room without increasing discomfort in the airways or joints during the full night.'
According to the NHS, the best way to cope in hot weather is to keep living spaces cool. This can be achieved by closing windows during the day and opening them at night when the outside temperature has dropped.
This comes as the Met Office issues a warning that an abnormally early heatwave could break records this week.
Pollen levels are also expected to be 'very high' for much of southern England and Wales.
Those who suffer from hay fever are advised to keep particles out of their eyes, face and hair by staying indoors where possible, medical charity Allergy said.
They are also advised to shower and wash their hair regularly and to remove the top layer of clothing when coming indoors to avoid spreading pollen particles around the house.