Investigators will recruit 120 patients with GERD in clinic who have to receive PPIs for four weeks and assess each volunteer before and after taking the medication. Assessment methods : 1. ANSWatch to assess the autonomic nervous system, 2. Ryodoraku to assess the energy of meridian system, 3. Upper gastrointestinal endoscopy to assess the grade of reflux esophagitis, 4. gastroesophageal reflux disease questionnaire to assess the severity of GERD. Investigators analysed and compared the database from the assessments between before and after taking the medication.