Drooling while sleeping is a common phenomenon, but if it occurs frequently in adults, it may be a sign of certain serious health conditions.

Where Does Saliva Come From?
The process of saliva secretion is controlled by the autonomic nervous system, functioning involuntarily like the heartbeat. The salivary glands in the mouth are divided into major and minor salivary glands. There are three pairs of major salivary glands:

Sublingual glands
Parotid glands
Submandibular glands

These salivary glands work continuously, keeping the oral environment moist, disinfecting, cleaning the mouth, and aiding digestion. In healthy adults, the amount of saliva secreted daily ranges from 1 to 1.5 liters, averaging about 30 ml per hour. Saliva secretion increases when eating or when the brain’s nerves are stimulated.