The transition into sleep is as much a thermal process as it is a chemical one. As your body prepares for sleep, your core temperature falls by about 1–2°F (roughly 0.5–1°C) through the evening and night, reaching its low point in the early morning. Anything that helps that drop tends to make falling asleep easier. (For the full picture of that daily low, see the core body temperature guide.)
The Warm Bath Paradox Explained#
Many people find that a hot bath before bed helps them sleep, especially about 1–2 hours before bed (Haghayegh et al., 2019, Sleep Medicine Reviews). This works because it triggers a response called vasodilation. Hot water draws blood to the surface of your skin, which lets heat escape from your core once you step out of the bath. That cooling is a signal the brain associates with sleep.
Thermal Environment Optimization#
- Room Temperature: Keep your bedroom between 60 and 67 degrees Fahrenheit (about 15.5–19.5°C). A cool room makes the necessary heat loss from your body easier.
- Warm Extremities: Wearing socks can actually help cool your core by dilating the blood vessels in your feet.
- Breathable Materials: Use natural fibers like linen or cooling bedding to keep heat from being trapped against your body.
Temperature is one part of a good evening; the rest is in our 3-2-1 wind-down routine. ARC's wind-down notification before your bedtime is a good cue to drop the thermostat.