Drooling during sleep is something many people feel embarrassed about, but the truth is that it can reveal a lot about how your brain and body are functioning at night. Far from being a sign of illness, nighttime drool is usually connected to relaxation, sleep stages, and how your nervous system controls the muscles of the mouth and throat. In this article, we explore the real scientific reasons behind nighttime drooling, when it’s normal, and when it might indicate a health issue.
Why Do We Drool at All?
Everyone produces saliva—about 1 to 1.5 liters per day. During the day, we swallow this saliva automatically without noticing. This is because the brain keeps the muscles of the mouth, tongue, and throat active. But when we sleep, the brain enters phases where these muscles relax, allowing saliva to escape from the mouth.
1. Your Brain Enters Deep Relaxation
One of the most common reasons people drool is because the brain has entered a deep sleep stage, especially REM sleep. During REM, your muscles relax almost completely. This includes:
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Jaw muscles
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Facial muscles
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Tongue control
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Swallowing reflex
When these muscles relax, saliva can naturally leak out of the mouth. In other words, drooling often means your body reached a deep, restful sleep, which is actually a good sign.
