For six years now, life has been really good for James. He has a great job as the creative director of an advertising firm in New York City. He enjoys spending time with his wife and kids.

And it has all been possible, he says, because for the past six years he has been taking a drug called ketamine.

Before ketamine, James was unable to work or focus his thoughts. His mind was filled with violent images. And his mood could go from ebullient to dark in a matter of minutes.

Ketamine “helped me get my life back,” says James, who asked that we not use his last name to protect his career.

Ketamine was developed as a human and animal anesthetic in the 1960s. And almost from the time it reached the market it has also been used as a mind-bending party drug.

But ketamine’s story took a surprising turn in 2006, when researchers at the National Institutes of Health showed that an intravenous dose could relieve severe depression in a matter of hours. Since then, doctors have prescribed ketamine “off label” to thousands of depressed patients who don’t respond to other drugs.

And pharmaceutical companies are testing several new ketamine-related drugs to treat depression. Johnson & Johnson expects to seek approval for its nasal spray esketamine later this year, though the approval would be limited to use in a clinical setting.

Meanwhile, doctors have begun trying ketamine on patients with a wide range of psychiatric disorders other than depression. And there is now growing evidence it can help people with anxiety, bipolar disorder, post-traumatic stress disorder, and perhaps even obsessive-compulsive disorder.

“I think it’s actually one of the biggest advances in psychiatry in a very long time,” says Dr. Martin Teicher, an associate professor of psychiatry at Harvard Medical School and director of the Developmental Biopsychiatry Research Program at McLean Hospital.

Ketamine may also offer new hope for people like James who have symptoms of several different psychiatric disorders.

James had a happy childhood, he says. But his thoughts were out of control. “I always felt like I was crossing a freeway and my thoughts were just racing past me,” he says.

He spent much of his childhood terrified of “an unknown, an ambiguous force out there.” The fear was “overwhelming,” he says. “I literally slept with the cover over my head with just room to breathe through my mouth until I went to college.”

And there was something else about James: his body temperature.

“I overheated constantly,” he says. “I would wear shorts all year long. In my 20s in my apartment I would sleep with the windows open in the middle of the winter.” To read more from Jon Hamilton, click here.