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

Part 2 of 2

For allergy sufferers, the moving air keeps particles like lint, pollen, and pet dander in circulation, allowing them to reach deeper into the lungs while you sleep.

Muscle Tension from Overnight Cooling

Another lesser-known effect of fan use is muscle stiffness. According to Dr Ali, prolonged exposure to cool air on muscles and joints may slightly reduce tissue temperature.

“Cool air against muscles and joints for seven or eight hours can cause a subtle drop in tissue temperature,” he said. “The chilled muscles tighten as a natural defense, and that tension may persist until a warm shower or gentle stretching restores normal blood flow.”

How to Use a Fan More Safely at Night

You don’t necessarily need to stop using a fan altogether. Dr Ali offers a few practical tips to reduce the downsides:

Use a timer so the fan shuts off after 90 minutes—roughly one sleep cycle.
Aim the fan away from the bed, preferably toward a wall.
Keep bedding clean to minimize airborne dust.
Keep a glass of water at your bedside in case your mouth or throat becomes dry.

“These small adjustments let the fan cool the room without increasing discomfort in the airways or joints during the full night,” Dr Ali added.

NHS Advice for Managing Heat at Home

The NHS recommends keeping your home cool during hot weather by keeping windows shut during the day and opening them at night when it’s cooler outside.

This advice comes as the UK faces the possibility of record-breaking heat, with pollen levels expected to remain “very high” across much of southern England and Wales.

Hay Fever Precautions During High Pollen Levels

Allergy UK advises hay fever sufferers to stay indoors as much as possible, and to take extra steps to prevent pollen from spreading indoors. These include: