Have you ever noticed wet spots on your pillow when you wake up? This common occurrence is usually caused by saliva. While it might seem strange or embarrassing, science explains why it happens.
Saliva is naturally produced by your salivary glands throughout the day and night. Its main role is to keep your mouth moist, help with digestion, and fight bacteria. When you sleep, your saliva production decreases, but certain factors can cause you to drool more than usual.
One major reason is your sleeping position. People who sleep on their side or stomach are more likely to let saliva escape from their mouths. Gravity works against you, and saliva can easily leak onto your pillow..Read The Complete Original.