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Reasons for drooling in sleep

Do you see saliva dripping from your mouth when you get up? Here’s why it happens.

Drooling while in a deep sleep is very common but have you ever wondered why it happens? It might seem harmless, but it could also  indicate a deeper problem. But before getting to that, let’s understand the connection between drooling and sleeping.

Medically, drooling is termed as sialorrhea (excessive saliva production) which is generally seen in infants while teething and sometimes in children with muscular problems and behavorial and neurological conditions like cerebral palsy.

There are different glands that contribute to the production of saliva. And the amount of saliva your body produces while you’re asleep is quite less than while you’re awake. In the resting state, the rate of secretion of saliva has been estimated to be 0.3 to 1 mL/1.7 m2/min. You don’t drool when you’re awake because you swallow up the saliva. But when you’re sleeping you’re relaxed and so are your facial muscles. Hence, whatever saliva the glands produce gets accumulated in your mouth, which then leaks out of the mouth because you don’t swallow it.

If you drool while sleeping, you must have noticed that saliva leaks out mostly when you sleep on your sides and rarely when you sleep on your back. That’s because, when you sleep on your back, saliva settles at the back of your throat and eventually drains down.

Coming to the clinical indications, drooling could be associated with the following mild to severe medical complications.

1. Allergies: Allergic rhinitis and certain food allergies cause over-production of saliva resulting in drooling. Read about six everyday things that can cause allergies

2. Acidity or GERD: Scientists believe that acid reflux episodes cause the gastric acid to stimulate the esophagus, as a result the esophagosalivary reflex gets excited leading to excessive saliva production.

3. Sinus infection: Upper respiratory tract infections are usually associated with breathing and swallowing problems, which cause drooling due to accumulation of saliva. Also, when your nasal passage is blocked due to flu, you tend breathe with your mouth, which causes the excess saliva to flow out while sleeping.

4. Tonsillitis: Tonsillitis is the inflammation of glands called tonsils present at the back of your throat. Due to inflammation and swelling the passage becomes narrow, thereby obstructing the drainage of accumulated saliva down the throat.

5. Sleep terrors: Drooling is a known symptom seen in people suffering from sleep terrors. Sleep terrors can be manifested in adults as a result of psychopathological reason. They often occur when a person in under severe emotional stress or may be triggered by certain drugs like sedatives, alcohol or even sleep deprivation. Sometimes, drooling is also seen in people suffering from other sleep-related disorders like sleep walking (somnambulism) and somniloquy (sleep talking).

6. Drugs and chemicals: If you’re on certain medications or if you’re taking drugs then drooling may be an everyday thing for you. Some antidepressants and medications like morphine, pilocarpine (treats dry mouth) cause increased saliva production.


+ Alexander KC Leung and  C Pion Kao. Drooling in children (
+ Drooling. Medical Encyclopedia (

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