Dry mouth and bad breath in bed at night may be caused by indigestion, poor oral hygiene, or Helicobacter pylori infection. 1. Indigestion: The accumulation of food in the stomach for too long can cause bad breath, in addition, the decline in gastric power leads to bile, stomach contents reflux and cause dry mouth, bitter mouth. 2. Poor oral hygiene: For example, if you don’t brush your teeth properly before going to bed, and there are food residues inside your teeth, it is easy to cause bacterial growth, which can lead to a series of problems such as oral infections, mouth ulcers, etc., resulting in the manifestations of dry mouth, halitosis, and bitterness in the mouth. 3. Helicobacter pylori infection: Helicobacter pylori infection leads to gastrointestinal dysfunction and gastrointestinal dyspepsia, while the stomach produces acidic gases, thus causing dry mouth, bad breath, bitter mouth and other phenomena. It is recommended to actively improve the relevant examination to find the causes of dry mouth and bad breath, and do a good job of cleaning teeth, especially pay attention to pathological factors, do not take it lightly.