What the evidence supports

The US National Heart, Lung, and Blood Institute recommends keeping the bedroom quiet, cool and dark as part of general healthy-sleep guidance.

Across the studies in the 2024 review, higher indoor or outdoor temperatures were generally associated with lower sleep quality or shorter sleep duration. The associations were more evident during hotter periods and among vulnerable groups.

That review does not supply one ideal bedroom temperature. Much of the evidence was observational, and the studies differed in their settings and methods. It therefore supports paying attention to heat, but not treating one number as a universal prescription.

Why a magic number is the wrong test

An exact thermostat setting can look precise while ignoring the limits of the evidence. A room described as cool in general guidance is not the same thing as a clinically validated temperature target.

A careful room test should answer a practical question: under otherwise similar conditions, what do you notice when the room feels warmer or cooler? It should not be used to prove that temperature caused a change in sleep.

A simple bedroom temperature log

Use the same short record for several nights:

  • Note the room temperature at bedtime if you can measure it.
  • Record whether the room felt cool, neutral or warm.
  • Note any unusually hot weather.
  • Record your bedtime and wake time.
  • Add a brief morning note about perceived sleep quality.

Look for a repeated pattern rather than drawing a conclusion from one night. The log is an observation tool, not a diagnosis or controlled experiment.

What not to conclude

The available sources do not establish:

  • one best temperature for every person;
  • a guaranteed improvement from changing the thermostat;
  • a personal treatment plan;
  • evidence that a cooling pillow improves sleep.

For the wider room setup, return to the Sleep Environment hub. You can also review the separate guides to white noise for sleep and blue light and sleep.

Sources

Common questions

What is the best temperature for sleep?

The US National Heart, Lung, and Blood Institute recommends keeping the bedroom quiet, cool and dark as part of general healthy-sleep guidance.

Across the studies in the 2024 review, higher indoor or outdoor temperatures were generally associated with lower sleep quality or shorter sleep duration. The associations were more evident during hotter periods and among vulnerable groups.

Is there an exact best temperature for sleep?

An exact thermostat setting can look precise while ignoring the limits of the evidence. A room described as cool in general guidance is not the same thing as a clinically validated temperature target.