system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can i spend the entire night tossing and turning, unable to sleep, and as soon as day breaks and I need to get up, I'm exhausted?

This may or may not be extremely relevant to my life.
gpt
The main reason for the sudden change is the daybreak itself. Your internal clock regularly resets/checks itself against the current level of light. In the dead of night it can't really tell between 1am and 3am for example, so when day starts to break the clock resets and realises it's actually morning and you instantly feel tired.

Have you ever been to a party/rave where you don't see the outside world all night, you get to the endm, still feel fine and as soon as you go outside or open the curtains or anything like that, you feel shattered? Same thing.