(FORTUNE Magazine) – Millions of people wake up at night with severe chest pain. Chances are it's not a heart attack but gastroesophageal reflux disease (GERD), commonly known as heartburn and caused by a glitch in the esophagus.

The esophagus meets the stomach just under the diaphragm, where a muscle called the lower esophageal sphincter (LES) prevents stomach juices and food from coming back up. Normally the LES relaxes only when you swallow. When it opens at other times, bitter acid flows up from the stomach and into the throat.

The classic GERD symptom, a burning sensation in the chest after eating, often occurs at night or when lying down. For some people, GERD symptoms are atypical--coughing, sore throat, wheezing.

GERD can be triggered by medications or foods that relax the LES--such as chocolate, caffeine, fatty or spicy foods, onions, mint, and alcohol. A hiatal hernia--when the stomach protrudes above the diaphragm--can also prevent the LES from closing. Obese people are more likely to have a hiatal hernia, which partially explains the association of obesity with GERD.

In up to 10% of people with long-standing reflux, the cells in the lining of the lower esophagus undergo a change (it's called Barrett's esophagus), increasing the risk of cancer. Cancer of the lower esophagus and upper stomach has risen in recent years, perhaps a result of the increase in obesity in this country. Some doctors believe that people with chronic GERD should undergo an endoscopy, an exam involving a scope that peers into the throat and stomach.

Great strides have been made in treating GERD. For occasional mild heartburn, antacids and lifestyle changes are often effective. Liquid antacids work a little faster than pills. Some antacids (aluminum) cause constipation; others (magnesium) cause diarrhea. Lifestyle changes may include avoiding the foods discussed above, losing weight, not eating within three hours of bedtime, and elevating the head of the bed a few inches.

If heartburn occurs regularly or is predictable--say, when you're going out for a big Italian meal--H2 receptor blockers are the next line of defense. Axid, Pepcid, Zantac, and Tagamet shut off the production of acid in the stomach. They don't work as fast as antacids, but they last longer and can be used preventively.

The big guns for GERD--proton pump inhibitors, or PPIs--are prescription drugs like Aciphex, Nexium, Prevacid, Prilosec, and Protonix. They're more effective than H2 blockers and have made a world of difference for patients with severe cases.

If the antacids, H2 blockers, and PPIs don't help, surgery may be the answer. Surgery that wraps part of the stomach around the LES is the old standby, but it occasionally causes serious complications. Newer laparoscopic surgery--a less invasive procedure, done through a smaller opening--is effective for some. Endoscopic procedures continue to be refined, including stitching up and tightening the lower esophagus.

Bottom line: If you're one of the many people suffering with GERD, you don't have to. Try one of the therapies mentioned above. You'll sleep better for it.

Donald D. Hensrud, M.D., is director of the Mayo Clinic Executive Health Program. For more on this topic, go to mayoclinic.com. Mayo Clinic offers Executive Health Programs in Jacksonville, Fla.; Rochester, Minn.; and Scottsdale, Ariz.