# The best bedroom temperature for sleep

Source: https://sleepfacts.uk/sleep-better/bedroom-temperature/
Author: Tess Marlow · Updated 2026-11-04

**Short answer:** A cool bedroom helps. Lab studies show that heat, especially humid heat, increases waking and reduces deep and REM sleep, because your body needs to shed heat to sleep well. Around 16 to 18°C is a commonly suggested range for a bedroom, but there is no tested single ideal: what matters is that you feel comfortably cool under your bedding.

**Evidence grade:** Moderate evidence. Trials point the same way but are small or few, or large long-term studies agree but cannot prove cause and effect.

## Why does temperature matter for sleep?

Your core body temperature falls in the evening and through the night as part of your [body clock](/how-sleep-works/body-clock/). To fall asleep, your body pushes heat out through the skin, especially the hands and feet. A small lab study found that how warm people's hands and feet were, a sign of heat flowing out, was the best predictor of how quickly they fell asleep. If the room is too hot, the body can't shed heat easily, and sleep suffers.

## What do the studies show?

A 2012 review of lab research on temperature and sleep found:

- **Heat** in real-life conditions, with bedding, increases waking and reduces both deep sleep and REM sleep.
- **Humid heat** is worse still, because sweat can't evaporate.
- **Cold**, with enough bedding, has little effect on sleep stages, though it affects the heart and is a risk for older people.

The studies are lab-based and small, but consistent, which is why we grade the evidence moderate.

## What temperature should a bedroom be?

There's no single tested ideal. Many sleep organisations suggest around 16 to 18°C, which works well with typical UK bedding. Treat that as a rule of thumb. What matters is that you feel comfortably cool, not cold, under your covers. Older adults and babies have less ability to regulate their temperature: for babies, follow safe sleep advice from your health visitor about room temperature and bedding.

## How do you keep cool in summer?

- Keep curtains or blinds closed on the sunny side during the day.
- Open windows when it's cooler outside, usually late evening and early morning.
- Use a fan, and sleep under a thin cotton sheet rather than a duvet.
- A lukewarm, not cold, shower before bed helps you shed heat.
- Avoid alcohol and big late meals, which raise body temperature.

## And in winter?

Keep the bedroom cool but use warm bedding. If your feet get cold, bed socks or a hot water bottle at your feet may help you drop off. If your home is very cold, the NHS advises keeping rooms you use at 18°C or above where you can, especially for older or vulnerable people, since cold homes carry health risks of their own.

## Frequently asked questions

### Is 20°C too warm for a bedroom?

Not necessarily. With light bedding and nightwear many people sleep well at 20°C. If you wake hot or sweaty, aim lower, use lighter bedding or open a window. Older people and babies are more sensitive to both heat and cold, so their rooms need more care.

### How can I sleep in a heatwave?

Keep curtains closed during the day, open windows when it's cooler outside than in, use a fan, sleep under a thin cotton sheet, have a lukewarm shower before bed, and drink enough water. The NHS heatwave advice also suggests checking on older relatives and neighbours.

### Do warm feet help you fall asleep?

They may. In a small lab study, how quickly people fell asleep was best predicted by how much heat their hands and feet were giving off. Warm feet widen blood vessels and help the core cool down. Bed socks are a reasonable thing to try if your feet get cold.

## References

1. [Okamoto-Mizuno K, Mizuno K. Effects of thermal environment on sleep and circadian rhythm. Journal of Physiological Anthropology, 2012.](https://pubmed.ncbi.nlm.nih.gov/22738673/)
2. [Kräuchi K et al. Warm feet promote the rapid onset of sleep. Nature, 1999.](https://pubmed.ncbi.nlm.nih.gov/10485703/)
3. [NHS. How to cope in hot weather.](https://www.nhs.uk/live-well/seasonal-health/heatwave-how-to-cope-in-hot-weather/)
4. [NHS Every Mind Matters. How to fall asleep faster and sleep better.](https://www.nhs.uk/every-mind-matters/mental-wellbeing-tips/how-to-fall-asleep-faster-and-sleep-better/)
5. [NHS. Keep warm, keep well.](https://www.nhs.uk/live-well/seasonal-health/keep-warm-keep-well/)