When you sing, musical vibrations in the form of frequencies move through your body, changing you both physically and emotionally. Group singing is the most transformative of all, especially when not accompanied by instruments. 

A cappella singing is about creating harmony with nothing but each other. It brings people together and is unmistakably human in a world that becomes more and more digital. Simply singing with other people is the ultimate analog.

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The elation comes from endorphins, a hormone released by singing, which is associated with feelings of pleasure. Oxytocin, another hormone released during singing, has also been found to alleviate anxiety and stress. Oxytocin also promotes feelings of trust and bonding, fueling more studies having found that singing lessens feelings of depression and loneliness. 

A recent study makes the case that "music evolved as a tool of social living," and that the pleasure that comes from singing together is our "evolutionary reward for coming together cooperatively, instead of hiding alone, every cave-dweller for him or herself".

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The benefits of singing regularly seem to be cumulative. In one study, singers were found to have lower levels of cortisol, indicating lower stress. Another investigation posits that our heart rates sync up during group singing, explaining why singing together sometimes feels like a guided group meditation.  

Singing is a form of regular, controlled breathing, since breathing out occurs on the song phrases and inhaling takes place between these. It gives you pretty much the same effect as yoga breathing. It helps you relax, and there are indications that it does provide a heart benefit.

-Dr. Björn Vickhoff

Study after study has found that singing relieves anxiety and contributes to quality of life. Dr. Julene K. Johnson, a researcher who has focused on older singers, began a five-year study to examine group singing as an affordable method to improve the health and well being of older adults in 2013.

It turns out you don't even have to be a good singer to reap the rewards. According to one 2005 study, group singing "can produce satisfying and therapeutic sensations even when the sound produced by the vocal instrument is of mediocre quality."