Body temperature drops during the night and reaches its lowest point before dawn.

The longer version

Core temperature follows a daily curve controlled by the body clock, falling through the evening under heat-loss mechanisms such as dilated skin vessels, and reaching its lowest point in the hours before sunrise. The drop is modest, around a degree, but it is remarkably consistent from night to night.

That trough coincides with the strongest sleepiness and slowest reaction times, which is one reason night-shift performance suffers. Falling temperature also helps initiate sleep, since heat loss seems to facilitate the transition. Hands and feet often feel warm at bedtime because blood is redirected outward to shed heat. Hibernators exaggerate the same mechanism dramatically.

Where this entry sits

This collection gathers curious details about sleeping and dreaming, from nightly brain stages and body clocks to naps, yawns and unusual animal habits. It also covers how bedtime customs have changed across centuries, without offering any advice. The full list sits on the Sleep and Dreams page, where every entry is listed in order.