Can singing a lullaby ease a child's pain?
Amid the beeping of heart monitors, a more gentle noise can be heard on the wards of Great Ormond Street Hospital.
The soft voice of musician Nick Pickett and the strumming of his guitar are entertaining the young patients in Bear Ward.
All the children here are under three years old. Some are facing the long wait for a heart transplant and are being kept alive by the rhythmic beating of a mechanical heart.
Sam Wallace's bed is surrounded by balloons, toys and other reminders of home. His grandmother, Viv Green, says the music has a transformative effect.
"Oh, Sammy loves music, he has always loved music.
Keira and Ian Bowers
Three-year-old Keira has been in hospital since the middle of June with heart failure.
She needs a Berlin mechanical heart, which helps her own heart pump blood around the body.
Her father Ian says the music makes a "big difference.
"It gives them a lift with the musical instruments, just to take their mind off where they are and the conditions they have.
"It perks her day up so it makes her feel wanted in a respect, so it does leave a lasting impression."
"It just makes him happy. He will sing and dance. He loves to dance, he moves with the music as soon as he hears it and it just brightens him up completely - he's a different boy."Improving moods
But is the bedside entertainment having a clinical benefit on children such as Sam? Can a rendition of Twinkle Twinkle Little Star actually help patients?
A team at the hospital and University of Roehampton tried to find out.
Thirty-seven children were played songs - including Five Little Ducks, See-Saw Marjorie Daw and Hush-a-Bye Baby - while nurses monitored their heart rates and assessed their pain levels.
The impact of the music was compared with storytelling or just leaving a child alone.
The results, published in the journal Psychology of Music, showed only music was reducing pain, slowing heart rates and improving the children's moods.
"It varies from child to child. Not every child wants to have music but for those that opt to have music I think it's very important for them," said Dr Pickett.
He added: "I think the most rewarding thing is if you are working with a child that is very distressed, a little one, and you go in, play some live calming, quiet music and watch the child go to sleep, that is great, it's the best reward."
One of the study's authors, David Hargreaves, of Roehampton University, is a jazz pianist as well as professor of music psychology.
As he sits playing a jazz interpretation of My Funny Valentine, he says the piece calms him down and makes him happy.
He says that kind of connection with music is shared even by young children: "Lullabies are something that children are familiar with. They're intended by parents to be used with their children to create relaxation and remove tension."
But is this just providing some evidence for what a lot of parents have realised for a long time, that singing to their children can soothe them?
The earliest records of lullabies can be traced to Babylonian times.
"I think it goes a bit further," he said.
"We are beginning to work out what aspects of the music affects what aspects of the physical and psychological response.
"Music has an effect on our thinking, our social behaviour, our emotions and our physical responses of course. What we are saying here is that children's wellbeing - their levels of anxiety and relaxation - are mediated by the emotion that the music causes."
End Quote Prof Tim Griffiths Consultant neurologist
What I think is happening here is that the emotional part of the brain is being stimulated by the music more so than the reading, and this is decreasing the arousal level of the children, and that in turn is affecting their pain response levels.”
The brain has a complicated relationship with music.
It is something Prof Tim Griffiths, a consultant neurologist with the Wellcome Trust and Newcastle University, has spent a career looking at.Much bigger role
He says the brain is analysing the musical melodies and separately responding emotionally.
"There are two parts to the musical brain. There is a part which processes sound patterns in the cortex and then there's a more ancient part of the brain which is responsible for the emotional responses to music."
It is a process that he says begins in the womb, so he was not surprised that children can benefit from music: "What I think is happening here is that the emotional part of the brain is being stimulated by the music more so than the reading, and this is decreasing the arousal level of the children, and that in turn is affecting their pain response levels."
The academic team admit their research is at an early stage, but are convinced music could end up playing a much bigger role in hospitals.