system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do bags form under our eyes when we don't get enough sleep?
gpt
It's because of gravity. When you're awake for a long time you're almost entirely in an upright position so gravity continuously pushes the retained fluids downward and it creates the bags. When you lay down facing up the fluid is then pushed into your body and travels to the air cavities where the body will do what it needs to with it. If you sleep brilliantly for a long time but on your stomach or on your side the bags don't go away bc gravity again is pushing them. Hence, it's recommended you sleep on your back and with your head propped up (also bc to keep composure of your cervical spine)