The voices that rise in unison to carry a song into your heart also synchronize the heart rates of the singers.
That's one of the findings of an unusual study published in the latest issue of the journal Frontiers in Neuroscience.
Bjorn Vickhoff, a professional singer and songwriter who's now a neuroscientist at the University of Gothenburg in Sweden, has long been interested in the effect of music on the human body, according to CNN.
So Vickhoff and his colleagues monitored the heart rates of 15 high-school choir members while they performed a variety of choral works. The research revealed that as the choir members sang in unison, their pulse rates sped up and slowed down at the same rate. [The 7 Biggest Mysteries of hte Human Body]
And the more structured the choral piece was, the more synchronous the singers' heart rates were. Vickhoff attributes much of that phenomenon to the effect of breathing on heart rate.
"When you exhale, you activate the vagus nerve, we think, that goes from the brain stem to the heart," Vickhoff told BBC. "And when that is activated the heart beats slower."
Other research has found that musicians performing together have synchronized brain waves. In a study published in 2012, researchers at the Max Planck Institute for Human Development in Berlin recorded the brain waves of 16 pairs of guitarists while they played a duet. In each pair of guitarists, the two musicians showed coordinated brain oscillations — or matching rhythms of neural activity — in regions of the brain associated with social cognition and music production.
"We already know that choral singing synchronizes the singers' muscular movements and neural activities in large parts of the body. Now we also know that this applies to the heart, to a large extent," Vickhoff said in a statement.
But can singing and playing music have a positive, lasting impact on health? That's a question that the researchers would like to investigate next.
"There have been studies on yoga breathing, which is very close to this, and also on guided breathing, and they have seen long-term effects on blood pressure ... and they have seen that you can bring down your blood pressure," Vickhoff told the BBC.
"We speculate that it is possible singing could also be beneficial," he said.
"Ultimately the knowledge that singing coordinates hearts is mind-blowing," Vickhoff told CNN. "If we, for instance, start singing a slow hymn together in church, we now know that the hearts in the hall are coordinated. And the thrilling question is: How does this affect us?"