Those who find themselves tossing and turning at night in the heat could find respite in the living room, as long as it is downstairs, a study suggests.
Researchers at Loughborough University found overheating to be more prevalent in bedrooms than in living rooms.
But the trend was reversed in flats and bungalows, which researchers said was because there tended to be more shade outside ground floor windows, keeping bedroom windows closed during the day, and the phenomenon of heat rising that causes upstairs bedrooms to heat up.
Researchers found more than 4.6 million homes in England are experiencing overheating during the summer.
The study suggests that people should "manage" bedrooms during the day to prevent heat build-up, by closing curtains and opening windows.
Prof Kevin Lomas, from Loughborough's School of Architecture, Building and Civil Engineering, who is lead researcher on the study, said that the threats posed by climate change were of global concern.
He said: "Heatwaves will increase in frequency, intensity, and duration, and so will the health risks associated with them.
"With the majority of fatal heat exposures in developed nations occurring indoors, the findings of our study show just how many homes in England are at risk of overheating."
The team said the risks associated with increased summertime temperatures indoors could be mitigated by better control over the methods of construction and refurbishment of flats, targeted public health messaging around overheating, and a call to building professionals to design and refurbish dwellings which are cool in summer as well as warm in winter.
The Climate Change Committee, the Government's statutory adviser, has estimated the costs of retrofitting cooling features into a property to be £9,200, compared with £2,300 when done at the building stage.