Always hungry in the middle of the night, may be physiological phenomena (eating too little, increased activity), duodenal ulcer, diabetes mellitus, hyperthyroidism and other causes. 1. Physiological phenomena: (1) eating too little: dinner food is relatively small, the energy is quickly consumed resulting in hunger in the middle of the night. (2) Increased activity: the daytime activity is relatively large, after dinner increased activity, resulting in hunger in the middle of the night. 2. Duodenal ulcer: stomach acid secretion at night when sleeping is more as well as the ulcer surface feels uncomfortable leading to always hungry, accompanied by acid reflux, stomach pain and other symptoms. 3. Diabetes mellitus: the disease manifests itself in symptoms such as hunger, thirst, excessive drinking and body wasting, so you are always hungry in the middle of the night. 4. Hyperthyroidism: due to excessive secretion of thyroxine, metabolism is too fast, which can cause hunger in the middle of the night, accompanied by sweating, increased appetite and other symptoms. It is recommended to consult a doctor as soon as possible to identify the cause, consult a physician and give standardized treatment.