Playing babies white noise to help them sleep may do more harm than good, a study has suggested.
Despite its popularity with new parents, researchers at the University of Pennsylvania School of Medicine in Philadelphia reviewed existing scientific research on white noise and concluded that the evidence base for noise generators is “very low”.
There may also be negative health effects from using noise machines if they lead to a more disrupted or fragmented sleep, Mathias Basner, a professor of psychiatry at the university said.
Many parents play their babies white noise from an app or specialist device to help them sleep at night.
The noise evens out differences in volume between ambient noise and a loud interruption – like a door slamming – by playing constant background sounds.
So-called “sleep machines” designed specifically for babies are available online for as little as £20 and phone apps that produce the sound are free.
“If these apps or devices could only do good things, I wouldn’t really care,” he said.
“But because there may be negative consequences, I would just be careful. I wouldn’t broadly recommend them, because there is no evidence that they are actually working.”
Prof Basner’s paper, published last month, concluded: “Additional research with objective sleep measures and detailed descriptions of noise exposure is needed before promoting continuous noise as a sleep aid, especially since it may also negatively affect sleep and hearing.
There is no official government guidance on babies and white noise, although a blog post on the NHS website does recommend new parents do not deliberately keep quiet when their babies are asleep, so they can become accustomed to background sounds.
One white noise generator for babies for sale at John Lewis and Partners can play the sound of lapping water and heartbeats “to reassure baby and lull them to sleep”.
The “White Noise Baby Sleep Sounds” App on the Google Play store has been downloaded more than a million times and claims to be “proven to be effective by generations of parents”.
Prof Basner is not the first medical professional to raise questions about sleep machines.
A separate study by the American Academy of Pediatrics (AAP) in 2014 tested 14 white noise machines designed for infants and found that all of them exceeded recommended noise limits for children.
Researchers said using white noise increased the risk of hearing problems and issues with language and speech development.
The research prompted paediatricians to issue advice that noise machines in bedrooms should be positioned 2m from the baby’s crib.
Colin Espie, a professor of sleep medicine at the University of Oxford, told the Guardian a hyperactive mind was more likely to disrupt sleep than background noise.
“Even the idea is a very limited one conceptually,” he said.
“The main concern to overcome in poor sleep is the busy or racing mind. People can’t switch off mentally. White noise is just like any other monotonous stimulation, which has been tried many times in many ways over decades, and the evidence [for it working] is poor.”