Stay up late may have bad breath, the causes are divided into physiological and pathological, pathological stay up late bad breath may be caused by gastric ulcers, gingivitis, etc., and should be promptly consulted to identify the cause. 1. Physiological factors: stay up late may eat due to hunger, such as consuming certain flavorful food, such as green onions, garlic, stinky tofu, etc., then the symptoms of bad breath may occur. It may also be a lot of smoking when staying up late, or not paying attention to the cleaning of the mouth after eating, etc., which can lead to the phenomenon of bad breath when staying up late. 2. Pathologic factors: (1) Gastric ulcer: gastric ulcer is a kind of peptic ulcer. Staying up late can affect the normal diet, due to the night snacks stay in the stomach for a long time, so that a large amount of gastric juice secretion, resulting in gastric mucosal erosion ulcers, and the gastrointestinal tract can be disturbed due to staying up late, causing bad breath. (2) gingivitis: due to the long time to stay up late to make the endocrine level rise, can cause gingivitis occurs, the patient can appear bad breath symptoms, but also can be accompanied by the root of the teeth local swelling, itching, discomfort, etc., as well as the color of the gums, the texture of the gums and other changes. Stay up late with bad breath, exclude physiological factors, should be timely consultation, if necessary, by the doctor to give targeted treatment. At the same time, it is recommended that the patient regular routine, try to avoid staying up all night, so as not to induce bad breath, affecting their life, social life.