Does ambient noise really help you get a better night’s sleep? | Canada Voices

The Sleep Whisperer is a series of columns offering insights and advice about sleep health. It is not a substitute for seeking professional medical care.

Have you ever gone to bed only to become hyper-aware of all the sounds around you: the traffic outside, the cat walking around, even your own heartbeat? For others, it’s not external noise but inner chatter that stands in the way of falling asleep.

A rapidly growing selection of ambient sleep noise apps and devices aim to tackle this problem. But whether it’s artificial white noise or the dull symphony of a humming fan, can background sounds really help us sleep?

In theory, background noise could mask sudden sounds that pop up at night, reducing the risks of awakening. Our auditory system is particularly reactive to unpredictable changes in our sound environment. Constant background noise in your bedroom may reduce the signal-to-noise ratio, making sudden disruptive sounds blend in and be more likely to go unnoticed.

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Indeed, some research suggests that continuous white noise reduces awakenings triggered by hospital sounds. Yet, in other studies, added background noise worsened awakenings, made the transitions between sleep stages more chaotic, and shortened sleep.

New research on pink noise

Does the type of ambient noise matter? White noise distributes energy evenly across the frequency spectrum, creating a hissing sound. Pink and brown noises weigh more heavily on lower frequencies, with a progressive decrease across the spectrum that sounds more like a waterfall or rainfall. Although some research has proposed that pink noise may be better than white noise, a study published in February by an international team, including Dr. Magdy Younes of the University of Manitoba, calls for caution.

In the study, researchers exposed healthy adults to disruptive sounds during the night — cars, jets and drones — and found that earplugs were much better at protecting sleep than pink noise. While pink noise slightly reduced sleep fragmentation, it also increased the time spent awake and cut down the amount of REM sleep, the sleep stage in which we most commonly dream. In a quiet environment, pink noise had no sleep-promoting effect and again reduced REM sleep.

Why would we care about losing some REM sleep? Because it contributes to emotion regulation, memory, neurodevelopment in children and brain plasticity at all ages.

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There are also concerns about hearing loss in the long term as a result of ambient noise. Quiet sleep supports the clearance of waste products in the auditory system but constant sound stimulation during the night may interfere with this restorative process.

Ambient noise and insomnia

What about people experiencing sleep issues, such as insomnia? Some researchers have proposed that regularly using ambient noise at bedtime could create a form of conditioning, in which these sounds become a cue for dozing off. So far, this remains a hypothesis. Scientific evidence is limited as most studies examining this were restricted to a short time frame and done in laboratory settings with small numbers of healthy adults.

One study designed to artificially mimic insomnia suggests that background noise may reduce difficulties falling asleep, but it’s unclear if this applies to people with real chronic insomnia. At Laval University, researcher Dr. Célyne Bastien has done extensive work showing that insomnia alters how we process sounds at night. For instance, blocking acute sounds during deep sleep is more taxing for the brain of someone with insomnia, a phenomenon associated with poorer sleep quality. Hence, people with insomnia may benefit more from strategies that make sudden sounds less likely to disrupt their sleep. However, it’s unknown whether background noise is the best strategy to accomplish this.

What to keep in mind if using ambient noise

Until the scientific evidence becomes more clear, here’s my advice about ambient noise and sleep:

• If you choose to use background noise, keep the volume as low as possible and set a timer to turn it off automatically after 30 minutes.
• Test a few silent nights — or try sleeping with earplugs — to see whether you wake up more refreshed. (If you are not actively aiming to use ambient noise, but are exposed to constant environmental noises during sleep, it may be worth experimenting with earplugs.)
• Carefully weigh the risks and benefits of exposing babies and children to background noise during sleep time. Your child may look like their sleep is less fragmented, but they could miss out on certain aspects of sleep that are important for healthy development.

Overall, when it comes to sleep, silence may be bliss.

Dr. Rébecca Robillard, PhD, is a clinical neuropsychologist and associate professor at the School of Psychology at the University of Ottawa. She also leads clinical sleep research at The Royal mental health hospital. Robillard’s main area of work focuses on interactions between mental health, the sleeping brain and the sleeping heart. She co-chairs the Canadian Sleep Research Consortium, a national hub of sleep scientists and clinicians.