system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What's the wierd taste in your mouth after sleeping?
gpt
A bunch of germs live in your mouth. Some of them are helpful germs, some are just germs leftover from the food you ate during the day. When you sleep, the bacteria don't. They are looking for food! They prefer carbohydrates, but your body doesn't make those naturally and you aren't eating them when you are asleep. So they break down the proteins found in your saliva. When they do that, waste gases are formed.  It is this waste that builds up in your mouth, which is what causes that bad taste and the bad smell of morning breath.