The key for older people to sleep well could be how hot or cold their room is. Researchers say the best way to sleep well is for the bedroom to be between 20-25º Celsius. The researchers are from Harvard University and an institute for aging research. They asked 50 people aged 65 and older to wear a sleep monitor for 18 months. The people's quality of sleep worsened when their room temperature was outside the 20-25-degree range. Researchers say 20ºC is the best temperature. They said: "Sleep tends to come easier and is often deeper…in a cooler environment."

The research is full of information. Temperature could affect sleep as much as having pain or drinking alcohol. The researchers found a 5-10 per cent drop in sleep quality when it was lower than 20ºC or higher than 25ºC. Poor sleep can lead to health issues, like an inability to think clearly, mood swings, and stress. Other problems include an increased risk of getting diabetes and heart disease. The researchers said people should create, "a more comfortable home environment" to sleep well. They also said climate change could affect sleep quality.