This isn't your typical choir practice. And it's not held in a traditional practice space either. These singers are all dealing with cancer, theirs or a loved one's. "There are people in our choirs who are undergoing treatment right now. There are some people who are waiting for treatment." Rosie Dow leads the choir groups at Tenovus Cancer Care, in the U.K. "We do have some terminally ill patients as well in our choirs, so people in palliative care. And then we also have people who've lost people to cancer. So carers and supporters." Anecdotally, chorus members have said that belting out tunes makes them feel good. But Dow and her colleagues wanted to see if that psychological effect might translate to a biological effect. So they selected five choir groups in Wales—with a total of 193 singers—and they took saliva samples both before and after an hour of singing. They found that singers had significantly lower levels of the stress hormone cortisol.