Causes of dry mouth during the night include side effects of certain medications such as diuretics, side effects of infections such as hypertension and side effects of treatments such as chemotherapy, states WebMD. In addition, dehydration, salivary glands excision, nerve damage and lifestyle also cause the condition.
Dry mouth, or xerostomia, is a condition where the mouth is dry and uncomfortable because it does not make sufficient saliva, explains WebMD. Saliva is important to the body as it wets and cleans the mouth, digests foods and prevents infection. Without sufficient saliva, a dry mouth increases the risk of developing tooth decay, gum disease and other infections of the mouth.