How Do We Know What Time It Is Without Looking at a Watch?

Imagine you're playing outside and suddenly feel sleepy. You might say, 'It must be nighttime!' That’s time perception, your body telling you what time it is without a watch.

Your brain uses things like light and how tired or awake you are to figure out the time of day. Like a biological clock, your body keeps track of when to sleep, eat, or wake up, even if there’s no clock around.