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Room Temperature Checker
The optimal bedroom temperature for sleep is 16–19°C (60–67°F). This range allows your core body temperature to drop by the ~1°C needed for sleep onset. Most bedrooms are too warm.
Unit
Optimal range
16–19°C · 61–66°F
Assessment
warm edge
Slightly above optimal. A 1–2°C drop will likely improve sleep quality. Switch to lighter bedding or lower thermostat by 1°C.
How it works
Sleep onset is initiated by a drop in core body temperature of roughly 1°C, which begins in the evening as part of the circadian rhythm. The body achieves this by routing more blood to the skin (especially the hands and feet) where heat radiates away.
A warm room slows that heat loss. Studies in controlled sleep laboratories (Okamoto-Mizuno & Mizuno, 2012; Lan et al, 2014) consistently find that rooms above 24°C increase wakefulness, reduce slow-wave sleep, and fragment REM. The exact optimum varies by bedding and clothing — but the 16–19°C range works across most setups.
Counterintuitively, a warm shower 60–90 minutes before bed speeds sleep onset, because the body responds with a stronger counter-cooling that completes by bedtime.