Chris Stephens, 28, who has been battling depression all of his life, plays with his dogs at home in Concord, Calif., on Friday. After a dose of ketamine, Stephens says, "I actually wanted to do things. I wanted to live life." Lianne Milton for NPR hide caption

itoggle caption Lianne Milton for NPR

While talking with the media outside the Exciting Idlewild Baptist Church in Lutz, Fla., on Sunday, former House Speaker Newt Gingrich called for a commission to look at new rules for clinics that perform in vitro fertilization. Matt Rourke/AP hide caption

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Ketamine has been used as an anesthetic for decades. It's also a widely popular but illegal club drug known as "Special K." When administered in low doses, patients report a rapid reduction in depression symptoms. Huw Golledge/flickr hide caption

itoggle caption Huw Golledge/flickr

Shannon Earle holds her new baby Kiera Breen Earle, moments after she was born at their home last year. Amanda Steen/NPR hide caption

itoggle caption Amanda Steen/NPR

Sue Freeman, 78, checks her email at her home in Laguna Beach, Calif., on Saturday. She says her eyesight improved markedly since she received an experimental stem-cell procedure last July. Melissa Forsyth for NPR hide caption

itoggle caption Melissa Forsyth for NPR

The antidepressant Prozac selectively targets the chemical serotonin. Paul S. Howell/Getty Images hide caption

itoggle caption Paul S. Howell/Getty Images