A good night's sleep is vital for optimal health. Not getting enough shut-eye can affect a person's mood and concentration the next day and it's been linked to a greater risk of chronic conditions, according to the National Heart, Lung, and Blood Institute.
Many factors affect sleep, from a person's wind-down routine to their environment. But if noise sometimes causes fragmented sleep, some people tout white noise as a potential solution. In theory, this low humming sound can help mask unwanted noises that disrupt sleep, thereby helping people to drift off. Yet research shows mixed results. So can white noise actually help you sleep better? We asked the experts.
What is white noise?
Natalie Barnett, the vice president of clinical research at Nanit, a sleep tech company in the U.S., told Live Science that white noise is a mixture of different sound frequencies and sounds like television or radio static.
It combines sounds of different frequencies at equal intensity, so that the ears perceive it as steady or even. Think of it as similar to white light — it appears white even though it contains a blend of different colors.
Can white noise help people sleep?
Some studies have shown white noise can improve some elements of sleep, but they have typically been small, with lots of variables that could muddy the results.
For instance, a 2021 study in the journal Sleep Medicine on 10 people living in a noisy neighborhood in New York City found that white noise helped mask environmental noise. Participants reported improvements in sleep quality and how long it took to fall asleep. Another 2017 study in the journal Frontiers in Neurology found white noise decreased the time it took between people turning their lights out and falling into stage 2 sleep by 38%. However, sleep quality did not change and the study was based on just 18 people.
For this reason, Jinyoung Kim, an associate professor at the University of Nevada, Las Vegas, told Live Science that it is still largely unclear whether white noise actually reduces the time it takes someone to fall asleep or improves sleep quality throughout the night.
"Many studies examine the effects in small samples and results are very inconsistent," she said.
There are also issues between objective measures of sleep quality — for instance, using a polysomnograph to measure brain waves — and subjective measures of sleep quality, such as self-reported hours of sleep.
"Some studies examine sleep quality and duration using questionnaires and report positive effects of white noise reducing frequent awake periods or increasing sleep time," Kim said. "But other studies with polysomnogram measures show no effects or even increased sleep fragmentation."
Ultimately, further research is needed to confirm whether white noise can help with sleep before it can be promoted as a sleep aid, concludes a 2021 review in the journal Sleep Medicine Reviews.
Even if future studies ultimately white noise can help with sleep, there are many unanswered questions..
"More research needs to be done to understand the mechanisms at play," said Barnett.
There are several unproven hypotheses. One possible explanation is that white noise could change a person's sensitivity to sounds.
"White noise may increase the hearing threshold level so that strong auditory stimuli are less capable of stimulating the cerebral cortex and disrupting sleep," Kim said.
Another theory relates to white noise mirroring brain waves. "Sound waves with certain frequencies may have sleep-promoting properties," Kim said. "For example, delta waves (0.5-4 Hertz) are similar to the brain waves generated during the deep sleep stage."
If white noise does help a person drift off, it may be because their brain links it to sleep, Barnett said. "White noise can become a sleep association, meaning that when someone hears white noise, it indicates it is time to sleep," she said. "When they wake at night, they hear the white noise and know they need to get back to sleep."
Whilst white noise is safe for most people, it could be problematic for people with tinnitus (a ringing noise in the ears), according to a 2018 review in the journal JAMA Otolaryngology, Head & Neck Surgery. Noise is also just one factor that affects sleep — other aspects of your environment and your night-time routine also have an impact.
