From boosting the brain to reducing pain, joining others in song can bring some wide-ranging benefits.
It's that time of year when the air starts to tinkle with angelic voices – or ring with the occasional lusty hymn – as carol singers spread their own indomitable brand of festive joy.
All that harking and heralding.
It's joyful and triumphant.
But these bands of tinsel-draped singers may be on to something.
Whether they realise it or not as they fill shopping centres, train stations, nursing homes and the street outside your front door with jubilant song, they are also giving their own health a boost.
From the brain to the heart, singing has been found to bring a wide range of benefits to those who do it, particularly if they do it in groups. It can draw people closer together, prime our bodies to fight off disease and even suppress pain.
So might it be worth raising your own voice in good cheer?
"Singing is a cognitive, physical, emotional and social act," says Alex Street, a researcher at the Cambridge Institute for Music Therapy Research who studies how music can be used to help children and adults recover from brain injuries.
Psychologists have long marvelled at how people who sing together can develop a powerful sense of social cohesion, with even among the most reluctant of vocalists becoming united in song.
Research has shown that complete strangers can forge unusually close bonds after singing together for an hour.
Perhaps unsurprisingly, there are clear physical benefits for the lungs and respiratory system from singing. Some researchers have been using singing to help people with lung diseases, for example.
Good vibrations
But singing also produces other measurable physical effects. It has been found to improve people's heart rate and blood pressure.
Singing in groups or choirs has even been found to boost our immune function in ways that simply listening to the same music cannot.
There are different explanations for this.
From a biological standpoint, it's thought that singing activates the vagus nerve which is directly connected to the vocal cords and muscles in the back of the throat.
The prolonged and controlled exhalation involved in singing also releases endorphins associated with pleasure, wellbeing and the suppression of pain.
Singing also activates a broad network of neurons on both sides of our brain, causing regions that deal with language, movement and emotion to light up. This, combined with the focus on breathing singing requires, make it an effective stress reliever.
"The 'feel good' responses become clear in the brighter sounding voices, facial expressions, and postures," says Street.
There could be some deep-rooted reasons for these benefits too. Some anthropologists believe that our hominid ancestors sang before they could speak, using vocalisations to mimic the sounds of nature or express feelings.
This may have played a key role in the development of complex social dynamics, emotional expression and ritual, and Street points out that it's no accident that singing is part of every human's life, whether musically inclined or not, noting that our brains and bodies are attuned from birth to respond in positive ways to song.
"Lullabies are sung to children, and then songs are sung at funerals," he says. "We learn our times tables through chanting, and our ABCs through the rhythmic and melodic structure."
Come together
But not all types of singing are equally beneficial. Singing as part of a group or a choir, for example, has been found to promote a greater level of psychological wellbeing than in solo singers.
For this reason, educational researchers have used singing as a tool for promoting cooperation, language development and emotional regulation in children.
Medical specialists are also turning to singing as a way of improving the quality of life of those living with different health conditions.
Around the world, researchers have studied the effects of joining dedicated community choirs established for cancer and stroke survivors, people living with Parkinson's disease and dementia, and their caregivers.
For example, singing improves the ability of Parkinson's patients to articulate, something which they are known to struggle with as the disease progresses.
Singing also represents a way of boosting general health as it has been shown to be an underrated workout comparible to a brisk walk.
"Singing is a physical activity and may have some parallel benefits to exercise," says Adam Lewis, an associate professor of respiratory physiotherapy at the University of Southampton.
One study even suggested that singing, along with various vocal exercises used by trained singers to hone pitch and rhythm, is a comparable workout for the heart and lungs to walking at a moderate pace on a treadmill.
But researchers are also keen to highlight the often under-recognised benefits of participating in group singing for the psyche of people living with long-term chronic illnesses.
Street explains that singing enables these people to focus on what they can do, rather than what they cannot.
"It suddenly brings an equality into the room where the caregivers are no longer caregivers, and the healthcare practitioners are also singing the same song in the same way," says Street.
"And there isn't really much else that does that."
Every breath you take
Among those who have been shown to benefit most from singing are people with chronic respiratory conditions, something which has become a major research focus for Keir Philip, a clinical lecturer in respiratory medicine at Imperial College London.
Philip cautions that singing will not cure people of these diseases, but it can serve as an effective holistic approach that complements conventional treatments.
"For some people, living with breathlessness can result in them changing the way they breathe, so that it becomes irregular and inefficient," says Philip.
"Some singing-based approaches help this in terms of the muscles used, the rhythm and the depth [of breathing], which can help improve symptoms."
One of his most notable studies involved taking a breathing programme which had been developed through working with professional singers in the English National Opera and using it as part of a randomised controlled trial in long Covid patients.
Over six weeks, the results showed that it improved their quality of life and alleviated some aspects of their breathing difficulties.
At the same time, singing isn't risk free for people with underlying health conditions. Group singing was linked to a superspreading event in the early stages of the Covid-19 pandemic, as the act of singing can emit large amounts of airborne virus. (Read more about how diseases spread as we talk and sing.)
"If you have a respiratory infection, it's best to miss that week at choir practice, to avoid putting other people at risk," says Philip.
But perhaps the most remarkable benefit of singing is that it appears to play a role in helping the brain repair itself from damage.
This was illustrated by the story of former US congresswoman Gabrielle Giffords, who survived being shot in the head during an assassination attempt in 2011.
Over the course of many years, Giffords relearned how to walk, speak, read and write, with therapists utilising songs from her childhood to help her regain verbal fluency.
Researchers have used similar approaches to help stroke survivors recover speech, as singing can provide the hours and hours of repetition needed to promote new connectivity between the two brain hemispheres, which is often damaged by an acute stroke.
Singing is also thought to enhance the brain's neuroplasticity, which allows it to rewire itself and create new neurological networks.
There are theories that singing may also help people suffering from cognitive decline because of the intense demands it places on the brain, requiring sustained attention and stimulating word finding and verbal memory.
"There is a gradually growing evidence base for the cognitive benefits of singing in older adults," says Teppo Särkämö, professor of neuropsychology at the University of Helsinki.
"We still know little though about the potential of singing to actually slow or prevent cognitive decline as this would require large-scale studies with years of follow-up."
For Street, all the research demonstrating the powerful effects of singing – whether at a social or a neurochemical level – underlines why it is such a universal part of human life.
One of his concerns, however, is that as people spend increasing amounts of time connected to technology rather with each other through activities like singing, relatively few people are experiencing its benefits.
"There's a lot we're discovering, particularly with rehabilitation from brain injury," he says.
"The studies are just starting to emerge which are showing that singing can have these effects, even for people with significant injury. It makes sense that we can benefit so much from it because singing has always played such an enormous role in connecting communities."
