Everyone has their own bedtime routines, whether it’s hugging a favorite pillow, sleeping in total darkness, or adjusting the blankets just right. But there’s one habit that many people share without even thinking about it — sticking a foot out from under the sheets. While it might seem like a quirky preference, science reveals that this simple action actually plays a key role in helping the body fall asleep and stay asleep.

According to María José Martínez, coordinator of the Chronobiology group at the Spanish Sleep Society, our bodies naturally cool down before sleep through a process called vasodilation. This happens when blood vessels in the hands and feet expand, allowing heat to escape. By extending a foot outside the covers, you help your body lower its internal temperature, which signals the brain that it’s time to rest. Babies display a similar behavior naturally — their warm ears and noses often indicate that their bodies are releasing heat to prepare for sleep.