system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you have a cold, why does your nose stop running while asleep?
gpt
Sometimes it doesn't, people have been known to wake up with snot all over the pillow. When it does stop it is normally because the nasal passages swell which prevent both snot and air from going through them. The nasal passages tend to swell completely shut when you are laying down. When you treat a cold with advil + sudafed you are dramatically reducing the swelling in the nose so you can blow the crud out of your nose more easily.