Singing boosts immune system

The scientists tested the blood of people who sang in a professional choir in the city, before and after a 60-minute rehearsal of Mozart's Requiem.

They found that concentrations of immunoglobin A -- proteins in the immune system which function as antibodies -- and hydrocortisone, an anti-stress hormone, increased significantly during the rehearsal.

A week later, when they asked members of the choir to listen to a recording of the Requiem without singing, they found the composition of their blood did not change signficantly.

The researchers, concluded that singing not only strengthened the immune system but also notably improved the performer's mood.