Dry mouth at night in bed. First, it may be caused by eating a lot of spicy and irritating food at night, it is generally recommended to drink a moderate amount of warm water, which can help relieve the phenomenon of dry mouth. Secondly, it may be caused by excessive smoking or drinking too much, in this case it is recommended to take proper rest and try to avoid these bad habits. Third, dry mouth at night may also be caused by professional reasons, such as teachers or lecturers, which often talk are prone to dry mouth. Fourth, sleep at night dry mouth may also be caused by environmental factors, such as indoor heat or dry air, are prone to dry mouth phenomenon, you can generally choose to use a humidifier or can more laundry drying in the room, improve the humidity of the room can relieve the phenomenon of dry mouth.