Nocturnal drooling, medically termed sialorrhea or ptyalism when excessive, is the unintentional loss of saliva from the mouth during sleep. While the body continues to produce saliva throughout the night, the muscular control and swallowing reflex that manage it during the day become significantly relaxed. This reduced control allows saliva to pool and escape. It is typically a benign mechanical issue, though sometimes it points to an underlying physiological factor.
How Sleep Position and Gravity Contribute
The simplest explanation for nighttime drooling relates to gravity and sleep position. When lying on the back, gravity assists in keeping excess saliva in the mouth or directing it down the throat to be swallowed. This positional advantage helps maintain a dry mouth and pillow.
Sleeping on the side or stomach removes this benefit, allowing gravity to pull saliva out of the mouth and onto the bedding. This effect is magnified when nasal congestion forces a person to breathe through their mouth. Mouth breathing means the lips are parted, creating an easy exit route for saliva not cleared by relaxed swallowing muscles.
The muscles in the face and jaw relax deeply during sleep, especially during the REM stage, making it difficult to maintain lip closure. This loss of muscle tone, combined with an open airway from mouth breathing, allows saliva to escape. Shifting sleep position or resolving temporary nasal blockage can often eliminate the issue entirely.
Underlying Health Conditions That Increase Saliva
While mechanics are often the cause, excessive drooling can also be a symptom of a health issue that either increases saliva production or impairs the ability to swallow.
Increased Saliva Production
Gastroesophageal Reflux Disease (GERD), or acid reflux, is a frequent contributor to increased salivation, sometimes called “water brash.” The irritation caused by stomach acid flowing back into the esophagus stimulates the salivary glands to produce more saliva as a protective mechanism. This increased volume makes it more likely that saliva will escape during the night.
Acute infections, such as strep throat, tonsillitis, or the common cold, cause inflammation in the throat and sinuses, making swallowing painful or difficult. This temporary impairment in the swallowing reflex, coupled with blocked nasal passages that promote mouth breathing, leads to increased drooling. Chronic issues like untreated allergies or a deviated septum also cause persistent nasal blockage, forcing mouth breathing nightly and exacerbating drooling.
Certain medications can cause hypersalivation (ptyalism) as a recognized side effect by chemically stimulating the salivary glands. Antipsychotic drugs, particularly clozapine, and some anticonvulsants are examples of medications known to increase saliva production. In these cases, the body is actively producing a greater volume of saliva, which the relaxed muscles cannot manage.
Impaired Swallowing
Neurological conditions like Parkinson’s disease or a previous stroke impair the oromotor movements and muscle control necessary for effective swallowing. This results in saliva spillage even if production is normal.
Practical Steps for Reducing Drooling
Addressing nocturnal drooling often begins with simple behavioral changes focused on adjusting sleep posture. Training oneself to sleep on the back is the most direct method, as gravity helps keep saliva at the back of the throat for swallowing. Using extra pillows to prop up the head or placing pillows along the sides of the body can help maintain a back-sleeping position.
Treating underlying respiratory issues is another effective strategy. Using saline nasal sprays or strips to clear congestion before bed encourages nose breathing and keeps the mouth closed. If allergies are suspected, consulting a physician for appropriate treatment can resolve the chronic nasal blockage that contributes to mouth breathing.
If drooling is persistent, professional intervention may be warranted. A dentist might recommend an oral appliance, similar to a mouthguard, which helps position the tongue and jaw to facilitate better lip closure and swallowing. For cases linked to medication, a doctor can review the prescription for alternatives, though no patient should stop a prescribed medication without medical consultation. In rare instances, a medical professional may discuss options such as speech therapy to strengthen swallowing muscles or the use of botulinum toxin injections to temporarily reduce salivary gland activity.