Listening to the "world's most relaxing song" before an operation could be just as good at calming patients' nerves as medication, US researchers say.
The song, written to reduce anxiety, blood pressure and heart rate, performed as well as a sedative in a study of 157 people.
But patients said they would have preferred to choose their own music.
And noise-cancelling headphones made communication harder, doctors said.
The University of Pennsylvania researchers, writing in a BMJ journal, now want to look at whether the type of music and how it is played to patients makes a difference to the results.
The patients in the trial were either given the drug midazolam or played the song 'Weightless' by UK band Marconi Union for three minutes, while having an anaesthetic to numb a region of the body.
Patient anxiety reduced by the same amount in both groups.
Feeling anxious before surgery can affect recovery because of the stress hormones produced in the body.
But drugs that reduce anxiety can have side-effects and need constant monitoring by doctors, the researchers from University of Pennsylvania said.
Music medicine, in contrast, was "virtually harm-free and inexpensive".
Dr Veena Graff, assistant professor of anaesthesiology and critical care from University of Pennsylvania Perelman School of Medicine, said: "Music lights up the emotional area of the brain, the reward system and the pleasure pathways.
"It means patients can be in their own world, they can be comfortable and have full control."