system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When your nose is congested, why does it get significantly harder to breath when sitting or laying down, but easier when standing up?

As the title says. This damn phenomenon has kept me up countless nights...
gpt
Most of the time when you are sick, the congestion is not from mucus and snot but instead inflamed and engorged tissue in the back of your nose. Laying flat increases the vascular pressure within these tissues, causing them to mechanically swell.