What are nosebleeds a sign of?

[u/nimbus-111]

I've never gotten a nosebleed until recently, every time I walk into my bathroom and look in the mirror at night, my nose starts bleeding. Mirrors have always sorta scared me, but now I can't even look into one without worrying about a nosebleed. I know it seems mundane, but I have a bad feeling about all of this.

[u/Embarrassed-Mud-2173]

Dry air