How does our body naturally wake up from sleep?

Question

As the title implies, how does our body (or any organism really) *know* when to wake up? Or how do we regain consciousness after we fall asleep?

In: Biology

Answer 1

You fall asleep when you are tired. You wake up when your body is done feeling tired. And when you do this repeatedly, rhythmically, it becomes a habit and your body gets used to it, and thus forms the basis of circadian rhythm. It also has a lot to do with REM, NREM sleep too but that’s a bit advanced stuff.