system
Given the following post, respond as if you're commenting on Reddit:
human
What's actually happening when you go temporarily blind for standing up too fast?
gpt
Your heart needs to pump at a slightly higher pressure to move the blood up to your brain, since it must now fight gravity. It takes a little while to adjust, so your brain becomes slightly blood (and oxygen) deprived for just a little while, causing your vision to momentarily degrade.