Normally, a muscle between the stomach and esophagus prevents reflux. When closed, this muscle keeps stomach contents from entering the esophagus. Reflux can occur if this muscle relaxes for an extended period of time. Alcohol and tobacco use can relax this muscle and contribute to symptoms. Body position can also affect reflux. Lying down can increase acid backflow into the esophagus. This is why some people have more symptoms when going to bed. Some foods can increase symptoms, including orange juice, coffee, and anything spicy. Acid reflux is also common during pregnancy.