As Britain experiences its third heatwave of 2026, many people are struggling to sleep in hot and humid conditions. While fans are a common solution, a frequently overlooked household appliance – the dehumidifier – may offer significant benefits, according to sleep expert Dave Gibson, founder of The Sleep Site.
How Humidity Disrupts Sleep
Gibson explains that the body relies on a drop in core temperature to fall asleep and stay asleep. “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.”
In humid air, sweat cannot evaporate efficiently, hindering the body’s natural cooling mechanism. 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.”
Optimal Humidity Settings
Gibson recommends setting the relative humidity to 40–60%. “Here I would avoid going dryer as it can make it uncomfortable to breathe by drying out your nose and throat which also increases snoring. It's worth getting this right in both directions. Equally if you leave a room with excess humidity, it can encourage dust mites, and even mould in some cases.”
Dehumidifiers also produce a gentle hum that can double as white noise, helping to mask sounds from outside and inside the bedroom.
Dehumidifiers vs. Fans
Gibson clarified that fans do not actually lower room temperature but can still be useful. “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 maximize a fan’s effect, it should be positioned to push hot air out through a window rather than simply stirring it around. Placing a tray of ice or a damp sheet in front of the fan can further cool the circulated air.
Dehumidifiers have become common in British households, with demand soaring during the cost of living crisis and rising energy bills. They are also cost-effective for drying laundry compared to tumble dryers.
