According to The Wall Street Journal, medical centers are increasingly using hypnosis to treat digestive conditions like acid reflux, irritable bowel syndrome and ulcerative colitis.

Most professionals who conduct hypnotherapy treatments are psychologists. Shoba Krishnamurthy, a gastroenterologist at the University of Washington School of Medicine, got training and decided to incorporate it into her practice about three years ago.

“It’s mostly for patients who have had a work-up but we haven’t found anything abnormal in tests, so there is not a specific abnormality to treat,” she says.

Studies have shown hypnotherapy is effective reducing symptoms associated with  gastrointestinal disorders. Insurance companies usually cover the treatments. The body of evidence is strongest for IBS, but a 2013 study found hypnotherapy was effective at prolonging remission in colitis patients. And a 2016 pilot study found patients with functional heartburn reported fewer symptoms.

The treatment usually consists of about seven sessions over three months, with home practice in between. Studies have found the effects can last more than a year and work in more than half of patients.

Experts theorize that hypnotherapy works because many gastrointestinal disorders are affected by a faulty connection between the brain and the gut, or digestive tract. The gut and brain are in constant communication. When something disrupts that communication, the brain misinterprets normal signals, which can cause the body to become hypersensitive to stimuli detected by nerves in the gut, causing pain. Experts believe hypnosis shifts the brain’s attention away from those stimuli by providing healthy suggestions about what’s going on in the gut.