As the UK endures its third heatwave of 2026, countless people are struggling to achieve a decent night's rest. Warm weather can make it more challenging to fall asleep and stay asleep because the body depends on a reduction in core temperature to trigger and sustain sleep.
Why Heat Disrupts Sleep
Dave Gibson, founder of The Sleep Site, explains: "Our core body temperature naturally begins to fall by around 0.5–1C as we fall asleep and through the first part of the night, but hot and humid conditions can prevent this cooling process from happening properly, leaving us tossing and turning throughout the night."
Many people turn to fans to stay cool overnight, but an often-forgotten household device may prove equally beneficial: the dehumidifier.
How a Dehumidifier Helps
Gibson told Marks Electrical: "In a humid bedroom, the air is already saturated, so the sweat can't evaporate from your skin. A dehumidifier literally removes that excess moisture in the air so your body's natural cooling can work effectively in the hot humid nights. I would set the relative humidity at 40-60%."
He advises against going drier than that, as it can make breathing uncomfortable by drying out the nose and throat, which also increases snoring. "It's worth getting this right in both directions," Gibson added. "Equally if you leave a room with excess humidity, it can encourage dust mites, and even mould in some cases."
Additional Benefits of Dehumidifiers
"One bonus of dehumidifiers is the gentle hum they produce which can double up as white noise and therefore masks sound from outside (and inside) the bedroom," Gibson noted. A growing number of British households now own a dehumidifier, with the devices surging in popularity amid the cost of living crisis and spiralling energy bills. Dehumidifiers can also be used to dry clothes and are considerably more economical compared with running a tumble dryer.
Fans: Still Useful but Not a Coolant
Gibson clarified that fans do not actually reduce the temperature of a room. Nevertheless, they can still prove useful when operated correctly. "The primary aim of any fan is to move air so that you get a flow passing over your skin. This then speeds up the evaporation of sweat." To maximise the benefit of a fan, it should be positioned to push hot air out through the window rather than just stirring it around. He further recommends placing a tray of ice or a damp sheet in front of it to additionally cool the circulating air.
