First, let’s get into what white noise is, and why people are using it. The more exact term, “Continuous Noise”, is a lasting and steady sound from a set of frequencies (Hz), filters, and power spectral densities (dB) – including, specifically, white noise. For us non-tech folks, it’s basically a steady sound played over a long period of time. It can be made by purpose built sound machines, fans, rain/showers, or even a growing number of apps available. The theory has been that it helps people fall asleep and stay asleep by potentially masking distracting noises, and providing a soothing sound.
Where the research comes from…
With the rising popularity of using white noise machines, especially with young children, there’s been increasing controversy the safety and effectiveness of it. A recent review, by a group from the University of Pennsylvania’s Perelman School of Medicine, has taken account of all the existing research available, and has published some interesting findings. I’d like to dive into the details of this review here, and make it easier for you all to digest the information.
Some researchers have worries that these noises can fundamentally change the way our brains process sound and potentially cause hearing loss. They have designed research to show exactly that. Some studies show marked sleep improvement in this type of sleep aid, also with a bias on a positive result. Concerned with the disparity among the short term benefits and long term effect, this latest review of the data included over 550 studies and research articles, and surprisingly found only 38 contained the proper evidence, human subjects, sound methodology, along with a lack of serious bias, to be credible enough to be included. What this means to the average parent, is that there is a lot of bad information floating around disguised as scientific evidence!
I took a deep dive into the relevant studies and the Perelman group’s conclusions to answer those initial questions posed…
Is it effective?
“Good sleep” is fundamentally measured by how long it takes a person to fall asleep (latency), how often they wake during the sleep period (fragmentation), and how long the sleep times last (duration). These studies do show evidence that there is a reduced amount of time needed to fall asleep for infants and children, primarily at times and conditions when their body is ready to sleep. The results are mixed for adults. The studies also show reduced waking for loud places (hospitals, city noises, etc) but no improvement in otherwise quiet places. Results indicated that sleep duration was improved in both active (REM) and quiet (non-REM) sleep in infants and children, but not adults. So – it would appear based on this review, sound-based sleep aids are effective in infants and young children, but they show less usefulness for teens and adults.
Is it safe?
These continuous noises have a masking effect on our brain’s ability to process and respond to sounds while we sleep. Biologically speaking, our ears don’t ‘turn off’ when we sleep, as a means of survival. When we have the white noise or similar sound playing, our threshold to respond other noises is raised, that is, the brain makes other noises less important and limits the need to respond. Scientists worry that we are turning off the protective mechanism we are born with, and could potentially be ‘re-wiring’ our brains to this lower state of sound awareness. Some scientists also fear that there are health concerns if our ears aren’t allow to rest along with the other parts of our bodies. There is a reason we sleep and let all the systems of the body recover; some believe this is just as important for the ears. Hearing problems have also been a major area of study, some touting that these noise machines are actually causing concerns like Tinnitus or hearing loss. The research team reviewing all the pertinent studies found no conclusive evidence for any of these concerns with the safe use of continuous noise. They did, however, give credence to the need for more investigation, as there were inconsistent measures across even the best studies for how loud and long the sounds were and also because of the low population sample sizes used.
So, what’s my take as a sleep expert?
It is clear that, in young children, proper use of white noise and similar sound machines is a positive addition to the sleep environment – at least for short term use. The frequencies used lower heart rate and respiratory rates, effectively calming the body. The sound also acts as a cue for infants and children that sleep is expected, enhancing the ability to teach good sleep habits and solidify routines. Let’s be honest, for many babies, the home is a noisy place during many of the hours they need to sleep. On average they need almost twice the amount of sleep as an adult! It makes sense to use the masking effects of the continuous noise during the times that the rest of the family is still awake. I believe it’s a combination of all these reasons that using white noise reduces the time it takes them to fall asleep, and why the children wake less frequently.
When we evaluate the known evidence-based risks, the volume of the sound is the most obvious concern. Any sound machine use for babies and young children should be kept at least 7 feet from their bed. The volume should be kept below 50-60 decibels. This is about the level of a normal conversation. If it sounds like a vacuum or a hair dryer, it’s too loud! As with anything we consider using around our babies, we evaluate risk versus reward, and the overall safety.
The current science shows that continuous noise – white, pink, brown or otherwise, used properly, is both safe and an effective tool for teaching and maintaining healthy sleep in children. If you’d like to know more about this, or are interested in looking into help teaching your little one to sleep more soundly or consistently, please reach out. I’d love to help.