Why do people experience drooling while sleeping and how common is it?

When you sleep, your body relaxes, including the muscles around your mouth. This means you do not swallow as often as when you're awake. Saliva naturally builds up, and because you are not actively swallowing, it can leak out, especially from the corners of your mouth. This drooling is a normal part of sleep for many people. It becomes more noticeable if your saliva production is a bit higher or if you sleep on your side.

Studies have shown that many people, even those who are otherwise healthy, drool a little bit during sleep because the muscles that normally help keep saliva inside are less active when you rest. In people with certain neurological conditions like Parkinson's disease or multiple system atrophy, the muscles and nerves may not work as well to control swallowing. This can make drooling more frequent or more noticeable.

Overall, drooling while sleeping is common, and while it might be a bit messy, it is usually not a sign of a serious problem. If it causes discomfort or you're experiencing other symptoms that concern you, try this free symptom checker to help understand what might be going on and whether you should see a doctor.