Breathing should be through the nose during a healthy sleep. However, some individuals develop the habit of sleeping with their mouth open due to nasal congestion, allergies or sleep apnea. This causes dry mouth and bacteria multiply more easily because the protective effect of saliva is reduced. Reduced saliva leads to caries, gum disease and bad breath. In order to prevent dry mouth during sleep, a moisture balance should be maintained in the bedroom, sufficient water should be consumed during the day and moisturizing mouth sprays should be used, if necessary, on the recommendation of a physician.