What causes drooling during sleep and when should you be concerned?

Waking up with a wet pillow is a common experience, but understanding the causes of drooling during sleep can help manage it. Saliva plays a vital role in digestion, dental health, and fighting pathogens, according to Dr. Mark Wolff, dean of the University of Pennsylvania School of Dental Medicine.

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Saliva is one of your body’s unsung heroes. It helps you taste and swallow food, protects your teeth from decay and helps keep harmful pathogens in check.

Drooling occurs when saliva accumulates faster than it can be cleared. During sleep, swallowing frequency decreases, and conscious control over mouth muscles weakens, as explained by Dr. Emily Boss, director of pediatric otolaryngology at Johns Hopkins Medicine. Mouth breathing exacerbates drooling by providing an easier exit for saliva. Gravity also contributes if one sleeps on their side or stomach, or nods off while sitting upright, according to Dr. Christine Won of the Yale Centers for Sleep Medicine.

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Without saliva, we’re in trouble.

Children naturally drool more as they develop muscle control and swallowing patterns, typically improving by age 4. Teething can also increase saliva production. For adults, simple adjustments can make a difference. Sleeping on one's back is often recommended to reduce drooling, though it may not suit individuals with sleep apnea. Using pillows to maintain this position can be helpful. Addressing nasal congestion from allergies or colds can also improve breathing through the nose and lessen drooling.

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Most of the time, drooling happens because saliva builds up faster than you can get rid of it.

Experts advise against mouth tape due to breathing concerns. Additionally, avoiding foods and drinks that stimulate saliva production before bed, such as sour items, sugary substances, and those that trigger acid reflux, can be beneficial. Eating too close to bedtime, especially spicy or greasy foods, should also be avoided. For those using dental devices like Invisalign or retainers, minimizing teeth grinding at night is also suggested.

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But while asleep, you swallow less often and have less conscious control over the muscles around your mouth.