Apparently, the secret to a great night's sleep isn't a fancy mattress or lavender spray. A new study found that Americans sleep best when their room is set to 67 degrees Fahrenheit, which, for Canadians, is about 19 degrees Celsius. RELATED: The “Perfect” Winter Thermostat Temperature (According to Science… Not Your Freezing Toes) ❄️🔥The findings also revealed that nearly half of women say they overheat at night, compared to just 38 per cent of men. Twenty-two per cent admit they can't agree on the bedroom temperature. The survey also found that:Seventy-eight per cent of people sleep with a fan on.