As the UK braces for a heatwave that could break May temperature records, sleep specialists are issuing an urgent warning against sleeping with a fan running, despite the temptation to seek relief from the soaring temperatures.
Heatwave Forecast
Temperatures are set to rise across the UK this Bank Holiday weekend, with 18 counties expected to experience 34°C or higher on Monday and Tuesday. The Met Office has indicated that highs of 35°C are achievable, potentially making these the hottest May days ever recorded. The current record stands at 32.8°C. According to the UKV weather model, Monday could see 34°C in Lincolnshire, while Tuesday may bring 35°C in London and the south-west.
Risks of Sleeping with a Fan
Many people have turned to oscillating fans for comfort during sticky nights, but experts caution that leaving a fan on overnight can cause more harm than good. Dr. Kiran Dintyala, speaking to Sleep Advisor, explained that fans continuously circulate dust and pollen, which can trigger severe reactions for allergy and asthma sufferers.
Additionally, the constant airflow dries out the room, potentially leading to dehydration, dry eyes, sinus infections, bronchitis, and nosebleeds. If you sleep with your mouth open, the dry air can cause a sore throat in the morning. Dr. Dintyala also noted that prolonged exposure to cool air can result in stiff, aching muscles upon waking.
Martin Seeley, chief executive of Mattress Next Day and a sleep specialist, supported these views, advising that fans should be kept off overnight regardless of how muggy conditions become. He warned that waking with itchy eyes, a runny nose, sneezing, or breathing difficulties could indicate that fan blades are coated in dust and directing it at you all night.
Additional Health Effects
Seeley added that even mild dehydration from the heat can worsen daytime drowsiness and fatigue. The persistent draft from a fan dries out nasal passages, prompting the body to overproduce mucus, which can lead to congestion, head pressure, and sinus headaches. Drinking water first thing in the morning can alleviate these symptoms. He also recommended avoiding directing the fan on areas with pre-existing muscle pain, such as from workouts or poor desk posture.
Ongoing Heatwave Conditions
The Met Office forecasts temperatures of 28°C or above until at least Thursday. An official heatwave is declared when temperatures meet the heatwave threshold—ranging from 25°C to 28°C depending on the region—for three consecutive days. Looking ahead to June, the outlook from May 28 to June 6 suggests continued fine weather and light winds, with high pressure expected to remain over much of the UK. However, there may be some showers and thunderstorms in the west on Thursday. Temperatures will stay warm or very warm inland, but cooler near the coast with an onshore breeze. Into June, more cloud and occasional rain are possible, but plenty of warm and dry weather is expected in between.
