system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: if the human brain doesn't have pain receptors why do people get headaches?

I have one now and it got me thinking.
gpt
Although it may feel like it, a headache is not actually a pain in your brain. The brain tells you when other parts of your body hurt, but it can't feel pain itself.
Most headaches happen in the nerves, blood vessels, and muscles that cover a person's head and neck. Sometimes the muscles or blood vessels swell, tighten, or go through other changes that stimulate the surrounding nerves or put pressure on them. These nerves send a rush of pain messages to the brain, and this brings on a headache.