All types of singing have positive psychological effects. The act of singing releases endorphins, the brain's "feel good" chemicals. Singing in front of a crowd, a la karaoke, naturally builds confidence, which has broad and long-lasting effects on general well-being. But of all types of singing, it's choral singing that seems to have the most dramatic effects on people's lives.
A study published in Australia in 2008 revealed that on average, choral singers rated their satisfaction with life higher than the public -- even when the actual problems faced by those singers were more substantial than those faced by the general public [source: MacLean]. A 1998 study found that after nursing-home residents took part in a singing program for a month, there were significant decreases in both anxiety and depression levels [source: ISPS]. Another study surveying more than 600 British choral singers found that singing plays a central role in their psychological health [source: ISPS].
But why? Could you just start belting out a tune right now in order to make yourself feel happy?
It's possible. Some of the ways in which choral singing makes people happy are physical, and you get them whether you're in a chorus or in a shower -- as long as you're using proper breathing techniques during that shower solo. Singing can have some of the same effects as exercise, like the release of endorphins, which give the singer an overall "lifted" feeling and are associated with stress reduction. It's also an aerobic activity, meaning it gets more oxygen into the blood for better circulation, which tends to promote a good mood. And singing necessitates deep breathing, another anxiety reducer. Deep breathing is a key to meditation and other relaxation techniques, and you can't sing well without it.
Physical effects, while pretty dramatic, are really just the beginning. Singing causes happiness for other reasons that have less of a biological basis.