Why might saliva flow from the mouth during sleep?

Sometimes, after waking up, you may notice a wet spot on your pillow. In most cases, this is a normal occurrence related to muscle relaxation during sleep. However, if excessive drooling happens frequently, it’s worth understanding the causes.

Saliva is produced by the salivary glands—sublingual, parotid, and submandibular. It is essential for keeping the mouth moist, aiding digestion, and protecting against bacteria. The nervous system regulates saliva production, and an increase in saliva flow can have various explanations.

Common causes:

• Sleeping position. Saliva often escapes when sleeping on your side or stomach, as facial muscles relax. Switching to sleeping on your back can help.
• Mouth breathing. If nasal congestion occurs due to allergies or a cold, a person may breathe through their mouth, leading to excessive drooling.
• Stress and fatigue. Sometimes, the nervous system responds to stress with increased salivary gland activity.

Excessive saliva production is known as hypersalivation. Possible causes include:

• Stomach disorders (gastritis, reflux, pancreatitis).
• Inflammation of the salivary glands or oral cavity issues.
• Nervous system disorders.
• Parasitic infections.

In some cases, saliva production is normal, but difficulty swallowing due to impaired throat muscles can cause drooling.

If it happens occasionally, there’s no need to worry. However, if the issue is persistent, consulting a doctor is advisable. A general practitioner (or a pediatrician for children) can assess the situation and refer you to a specialist—such as a dentist, gastroenterologist, neurologist, or ENT doctor—if necessary. Tips to reduce excessive drooling:

• Try sleeping on your back.
• If the skin around your mouth becomes irritated, apply a moisturizing cream.
• Avoid carbonated drinks, sweets, and heavy broths before bed.

Treatment depends on the cause—some cases require dietary and lifestyle changes, while others may need medication or, in rare instances, surgery.

Regular medical check-ups, maintaining digestive and nervous system health, and seeking timely medical attention for concerning symptoms can help prevent excessive drooling.