Hi Dear , As per your query you have severe coughing and green mucous at night and it is normal at day time . Well there can be many reasons for symptoms you mention in query by it seems to me there are two probable reasons for this :- First there is acid reflux . in which esophageal sphincter not fuction normally and stomach content , which is acidic come upward upto throat and cause irritation or coughing . Secondly there is chances of viral infection of upper respiratory track . You should consult gastroenterologist for proper examination . Doctor may order endoscopy , ultrasound for pancreas and X-ray of upper digestive track along with other tests . Doctor may prescribe drugs like omeprazole and ranitidine . Doctor may also refer you to ENT specialist if he/she found problem to be occur due to upper respiratory track infection . For now avoid eating spicy and heavy meal specially at night , eat at least one hour before going to bed , take light walk after every meal , elevate your head while laying down and take antacid (gelusil ) after every meal . Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari