system
Given the following post, respond as if you're commenting on Reddit:
human
Why do our breath stink when we are hungry?
gpt
Hunger triggers a primal instinct to act & search/hunt for food. It does this by stimulating your stress hormones, cortisol and adrenaline. When you have an adrenaline rush (like when you're scared or nervous), your mouth dries up. This is because adrenaline inhibits saliva production. Salivating is not much use when running from a predator!

Saliva is a natural cleanser for the mouth. A dry mouth will soon start to smell bad as bacteria grow and secrete waste.

This phenomenon also happens when you sleep. Saliva production mostly slows down when you're asleep, which is a large part of why you wake up with bad breath.