system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does everyone have a “morning face”? You can always tell when someone has just woken up. What causes this to happen physically?
gpt
Most people sleep laying down.  Fluids in the body have a chance to equal out so the face looks a little fuller, eyes a bit more shut etc...  ever notice how ankles are swollen usually at the end of the day?  Same thing, all the fluids have drained downwards.