Why your body cools down before sleep
Sleep is tied to a daily rhythm in body temperature. As evening approaches, the body begins releasing heat, including through the skin of the hands and feet. Its internal temperature then gradually falls. That shift is one of the cues that helps prepare the brain and body for sleep—not a switch that causes sleep on its own.
A cooler room makes heat easier to lose
Your body continually produces heat, and it has to shed some of it to cool down. In a warm, stuffy bedroom, the temperature difference between your skin and the surrounding air is smaller, so heat escapes less readily. Warmth can also make you sweat; if that moisture cannot evaporate comfortably, you may feel sticky and restless.
A comfortably cool room gives your body a better chance to release heat as its temperature follows its evening rhythm. It does not need to be cold enough to make you shiver: shivering is the body generating extra heat, the opposite of a restful wind-down.
Comfort is the practical test
There is no single room temperature that suits everyone. Bedding, clothing, humidity, and personal comfort all affect how warm you feel. If you are waking because you are hot, try lightening the covers or improving airflow before making the room dramatically colder.
The useful target is not maximum cold, but a bedroom that lets you settle without overheating. A small change—such as using a lighter blanket—can help your body lose heat without turning bedtime into a test of endurance.
