system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does my breath stink in the morning even though I brushed/flossed/mouth washed before i went to bed?
gpt
At night your mouth doesn't produce saliva.  Saliva helps to reduce the amount of bacteria in your mouth.  But when your mouth is dry at night, bacteria multiplies because there isn't much saliva to control it.  When you brush your teeth before going to sleep it doesn't get rid of all the bacteria.  Bacteria is everywhere and you can't get rid of it all.