The UK’s first major heatwave of 2026 is well underway, leaving many Brits struggling to sleep over the weekend – but an expert has told households to limit overnight fan use to one hour until Thursday.
On Monday, the UK recorded its hottest ever May temperature after 34.8C was provisionally logged at Kew Gardens in London, surpassing the previous bank holiday Monday record of 33.3C set in 2019.
Wales also experienced its hottest May day on record, with temperatures reaching 32.2C at Hawarden Airport in Flintshire, while the Met Office described the heat as “exceptional in the UK even in mid-summer, let alone in May”.
The soaring temperatures prompted the UK Health Security Agency to issue its first amber heat-health alert of 2026 across much of England.
The alert will remain in place until Wednesday, with health officials warning people to stay hydrated as temperatures remain far above the seasonal average of 14C to 20C.
With many people turning to electric fans overnight to cope with the heat, sleep expert Martin Seeley from MattressNextDay warned you should never leave it on for more than one hour.
“Let’s be clear: there’s nothing wrong with using an electrical fan to cool down your room as long as you only use it for a short period of time,” Martin said.
“I’d recommend turning your fan on 30 minutes before bed, then setting a timer for around 60 minutes once you go to sleep. This helps cool the room without exposing yourself to the risks of constant airflow throughout the night.”
According to Martin, keeping a fan running throughout the night can circulate dust and allergens, dry out your eyes and skin, trigger headaches and even cause muscle stiffness if the airflow is directed at your body for long periods.
He also warned that excessive cooling could interfere with the body’s natural sleep cycle, potentially leading to restless or fragmented sleep.
Instead, Martin recommends a number of alternative ways to stay cool overnight until termperatures cool on Thursday.
- Using the “Egyptian method” by sleeping under a slightly damp sheet
- Cooling pulse points like wrists and feet with cold water
- Creating cross-ventilation by opening windows on opposite sides of the room
- Freezing socks or a bandana before bed
- Wearing lightweight cotton or bamboo pyjamas instead of sleeping naked
He also advised avoiding alcohol before bed during hot weather, as it can raise your core body temperature and disrupt sleep further.
Temperatures are predicted to ease from Thursday, but forecasters say parts of England and Wales could still remain in the high 20s.