What Is the Best Bedroom Temperature for Sleep?

A cool bedroom, roughly 18–20 °C (65–68 °F), is the range most sleep researchers recommend. Core body temperature needs to drop by about 1 °C to initiate sleep, and a cool room makes that easier. Individual comfort varies, so treat the range as a starting point rather than a rule.

How it works

Sleep onset is tightly coupled to a fall in core body temperature. In the evening, blood flow shifts to the hands and feet, radiating heat away from the core. A cool environment accelerates that heat loss; a warm one fights it, which is why hot summer nights fragment sleep.

Protocol

• Set the thermostat to around 18–20 °C (65–68 °F) an hour before bed.
• Use breathable bedding so you can shed layers overnight.
• A warm shower or bath 1–2 hours before bed can paradoxically help: the warm water dilates blood vessels in the skin, speeding core cooling afterwards.
• Keep hands and feet warm (socks are fine) while the room stays cool.

What the research says

Harding, Franks and Wisden (2019) review the physiology linking thermoregulation to sleep and summarise evidence that both sleep onset and slow-wave sleep are sensitive to ambient and skin temperature. Most of the evidence comes from laboratory studies with small samples, so the exact optimal temperature is less certain than the direction of the effect.