Light brown saliva in the mouth every night may generally be related to gingivitis, periodontitis, upper gastrointestinal bleeding and so on. It is recommended that patients go to the hospital in a timely manner to clarify the cause of the disease. 1. Gingivitis: refers to the inflammation of the gum tissue caused by plaque and other factors, which can cause bleeding gums, gum color, shape and texture changes. A small amount of bleeding gums leads to light brown saliva. 2. Periodontitis: a chronic infectious disease of the periodontal tissues caused by plaque biofilm, the gums are bright red or dark red, bleeding, pus spillage, etc.. It leads to light brown saliva in the patient’s mouth. 3. Upper gastrointestinal bleeding: patients with a small amount of upper gastrointestinal bleeding can have light brown saliva, accompanied by black stools, blood in the stool, dizziness, panic, fatigue, fever and other symptoms. Most of the light brown saliva in the mouth every night is related to bleeding, and it is recommended that the patient go to the hospital in time to clarify the cause of the disease, and follow the doctor’s instructions on the cause of the treatment.