Your brain may be resting, but your sleeping position also contributes. People who sleep:
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On their side
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On their stomach
…are more likely to drool because gravity pulls saliva downward. If the mouth opens slightly, saliva has an easy way out.
Sleeping on your back, on the other hand, usually reduces drooling because saliva flows toward the throat and triggers swallowing.
3. Your Brain May Be Producing More Saliva Than Usual
Sometimes the brain stimulates extra saliva production while sleeping. This doesn’t mean there’s something seriously wrong. It can happen if:
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You recently ate spicy or acidic foods
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You consumed foods that stimulate saliva (lemon, ginger, garlic)
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You were sleeping with your mouth slightly open
When the salivary glands are active and the swallowing muscles relax, drooling becomes more likely.
4. Nasal Congestion Changes How You Breathe
When the nose is blocked, your brain forces the body to breathe through the mouth. Mouth breathing increases drooling because the mouth stays open through the night. This is common during:
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Allergies
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Colds and flu
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Sinus infections
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Deviated septum
In these cases, drooling is simply a side effect of mouth breathing—not a dangerous symptom.
