Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. As per your complain dry mouth can occur due to causes like Severe dehydration, Side effects of medications if you take any, Salivary gland dysfunction, Nerve damage supplying salivary glands, Oral infections like thrush, Sjogren s Syndrome..etc.. As it occurs at night it can be commonly sue to mouth breathing habit, and in case if you are not aware of it may be you breathe through mouth while in deep sleep. -For dry mouth chew sugarfree chewing gums.. -Drink plenty of water. -Avoid regular mouthwash and use specialized mouthwash that are formulated for dry mouth patients like Biotene.. -You can also instil artificial saliva drops.. -Suck tart candies as it also stimulates saliva flow.. If it occurs at night then you can apply Xylitol patches inside mouth as it helps in maintaining a lubricating layer inside mouth. If does not improve consult an Oral Physician and get evaluated.. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Honey Arora