You've probably awakened with a mouth that feels as if it's filled with cotton. It's called dry mouth, and while not dangerous in itself, it can be very uncomfortable. We identify dry mouth with being thirsty, and this lack of moisture can be disconcerting. But the explanation for dry mouth early in the morning is often simple.
Identification
Dry mouth is as it sounds -- you will wake up with very little saliva or moisture in your mouth, making talking and swallowing more difficult. The tongue and inside of your mouth likely feel much rougher, and you may feel very thirsty.
Saliva Production
The common explanation for dry mouth is as simple as saliva production: when you sleep, less saliva is produced. Because saliva is mainly a lubricant, it's not as important at night, and the lack of stimulus, either talking or eating, often causes the body to shut down the saliva-producing glands, or to at least minimize their output. As saliva is swallowed or evaporates during the night, dry mouth develops.
Dehydration
If you aren't drinking enough water during the day, you may experience dry mouth because you're dehydrated. We perspire and lose water while we sleep, and if you go to bed with low water content in your body, by the time you wake up, it may be crying out for a drink. For some, a combination of decreased saliva production and dehydration can cause dry mouth.
Treatments
Taking frequent sips of water throughout the day and in the morning can help treat and prevent dry mouth from occurring. A humidifier in your home may also make it easier for you to retain moisture in your mouth overnight, and chewing gum or eating will stimulate saliva flow, as will brushing your teeth. You should also avoid drinking caffeinated beverages at night; these can dehydrate you and cause morning dry mouth.
Considerations
You may be taking medications that cause dry mouth. If so, consult your doctor about this side effect before discontinuing their use, as the dry mouth alone is not a serious condition. If you develop dry mouth in association with other unexplained symptoms or conditions, inform your doctor. You should also try to promote nighttime breathing through your nose; this can curb oral dryness.
