Volunteers who went to two music concerts, by the composer Eric Whitacre, saw a reduction in their levels of the stress hormones cortisol and cortisene.
Researchers studied the 117 concert-goers at the events at Gloucester Cathedral and the Union Chapel in London, testing saliva samples given before the performances and during the interval an hour later.
The researchers found unanimous drops in both hormones in the second set of samples and described it as the first time.
"[T]his is the first time that such decreases have been found not only in tightly controlled laboratory settings but in the naturalistic setting of a public concert in a cultural space," Daisy Fancourt, research lead, from the Centre for Performance science (a partnership between Imperial College London and the Royal College of Music), said in the study.
While cortisol can have a beneficial effect on the body when it is released in small doses, long-term release through chronic stress can worsen medical conditions such as diabetes and heart disease, and can impact the immune system.
The researchers found the calming effects of the classical music concerts were not associated with age, musical experience or familiarity with the music being performed.
However, as the study only surveyed "relatively calm, classical music", it's unclear how loud music gigs, rock or pop concerts would affect people's stress levels.