Why We Drool in Our Sleep: What Your Brain Is Really Doing When You Rest

Contrary to what it may seem, the brain doesn’t go quiet when we drift off—it becomes incredibly active. Throughout the night, it cycles between non-REM sleep, which restores the body, and REM sleep, where we dream most vividly.

During REM sleep, the body’s muscles reach a state of deep relaxation, almost like temporary paralysis. This helps prevent us from acting out our dreams but also means the muscles controlling the mouth and jaw relax completely.

Even though saliva production might slightly decrease in this stage, the lack of muscle control makes it easier for any saliva that remains to escape. The brain detects what’s happening but can’t override it—it’s too busy performing essential “maintenance work,” such as consolidating memories, repairing tissues, and regulating hormones.

In other words, that drool on your pillow is physical proof that your body was busy healing and balancing itself while you slept.

Why Some People Drool More Than Others

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