Mentioned in: _ Why we sleep
Tags: Health

Definition and properties of sleeping

How we understand other people sleep:

1. Horizontal position.
2. Lowered muscle tone.
3. No displays of communication and responsivity.
4. Easily reversible.
5. Has reliable time pattern in 24-hours window.

How we understand we sleep:

1. Loss of external awareness. You don't react to the world.
2. Loss of sense of time.
3. Dreaming.