system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] Why are our eyes sometimes blurry within the hour or so after we have woken up from a night's sleep? Why is it sometimes one eye more than the other?
gpt
If you sleep with your head into the pillow or your arm over your eye, the pressure temporarily deforms your eye.  Your eyes' lenses can't focus correctly onto the back of the eye when they are deformed.  This means everything is blurry as if you needed glasses.  Your eyes move back into their normal shape over time.


Glasses or contacts are needed permanently when eyes default shape isn't correct to make up for the error.