Hey,thats because of secreation of gastric juice  throughout night,  try eating  small meals instead of three large ones whenever you can.  Avoid foods that irritate your stomach, especially those that are spicy, acidic, fried or fatty. Alcohol can irritate the mucous lining of your stomach. Stress may make your gastritis symptoms worse. Stress may be hard to avoid, but you can learn to cope with it. If you have trouble relaxing, consider calming activities, such as meditation, yoga