Question

why do people drool in their sleep?

Answer 1

People cant help drooling in their sleep. Everything enters a relaxed state and control of body functions becomes difficult. Drooling is more evident in people who breath through their mouths.

"The salivary glands are in continuous production, generating saliva to lubricate the mouth. Saliva production increases when people eat. The mouth is designed to help people retain saliva and people regularly swallow to allow the saliva to drain into the stomach so it can be eliminated from the body. While asleep, the mechanisms for keeping saliva in the mouth and swallowing it may not function as well; swallowing reflexes, for example, can be less active during sleep...People may also find that they experience drooling while sleeping when they are not feeling well...In babies, drool during sleep is very common because the reflexes involved have not formed and been refined yet." - http://www.wisegeek.com/why-do-we-drool-while-we-sleep.htm

Also, "Drooling can be normal, but it can also be associated with other medical conditions." - http://www.webmd.com/sleep-disorders/features/8-embarrassing-sleep-secrets