Nighttime noise can affect your health—even if you're asleep
When I chose an apartment with a bedroom on a major street in Manhattan, I didn’t worry about noise: I figured this was one instance in which my hearing loss was a plus. Sounds that didn’t wake me up couldn’t affect me, right?
Wrong. Waking up and losing sleep because of noise is bad for your health, but according to the World Health Organization, the biggest global health danger of noise pollution comes from the effects of noise we’re not consciously aware of while sleeping. It doesn’t have to wake you up to affect your sleep.
And as I learned later, hearing loss in itself may be linked to sleep disturbance, making us more vulnerable. However, scientists haven’t explored how noise at night specifically affects people with hearing loss; it’s “a niche that needs a lot more research,” observes Nancy Tye-Murray, PhD, audiologist and professor at Washington University School of Medicine in St. Louis.
How noise disrupts your sleep and your health
Chronically disturbed sleep—or too little sleep—is linked to obesity, diabetes and high blood pressure. People exposed to nightly traffic noise are more likely to have heart disease and to take sleep medicine, which doesn’t restore their sleep quality completely.
While asleep, you cycle through two kinds of light sleep (stage 1 and 2), deep slow-wave sleep (stage 3), and rapid-eye movement (REM) sleep (stage 4). During stage 3, your muscles relax and your pulse and breathing rate slow. This stage may be critical for the immune system. Stage 4 sleep, when your dream, is important for memory, learning, and creativity.
Noise seems to lengthen stage 1 sleep and decrease both stage 3 and stage 4 sleep. It also may trigger alarm signals in your body like the hormones adrenaline and cortisol. Your heart rate and blood pressure may rise. This happens even though you don’t wake up. In effect, your body is guarding you while you rest.
Being receptive to danger in the night was no doubt useful for our ancestors—but if you’re not sleeping in a cave near a savannah full of wild animals, it means unnecessary alarm. Interestingly, the noise doesn’t have to be loud: In one study, hospital equipment (about 40 decibels), showed a measurable impact in electroencephalogram (EEG) measurements of the brain activity in sleeping healthy adult volunteers. It triggered more activity (suggesting alarm) nearly all the time during stage 2, which is about half of the night for adults.
For more information on the health effects of noise, see “What is noise pollution?”. You might think of it as “secondhand sound” like secondhand smoke.
What if you have hearing loss? Are you less at risk of a sleep problem?
Sadly, no. A 2019 “scoping review” evaluating what we know so far concluded that hearing loss is linked to insomnia and other sleep disturbances. How night noise fits in remains unknown. Study author Nathan Clarke, who researches hearing loss at the University of Nottingham notes, “From an evolutionary perspective, it is not unreasonable to suppose that people with hearing loss may have to work harder to process dangerous nighttime noise. However, the available data is sparse.”
Tinnitus can make things worse. In a study of nearly 300 Israelis exposed to industrial noise, those with ringing in the ears had the most sleep problems, but hearing loss alone was linked to insomnia, regardless of age or how long they’d been exposed to the noise. (Be sure to listen to white noise or something similar when falling asleep, as this can help you get deeper sleep by masking the tinnitus.)
People with hearing loss are more likely to sleep for more than eight hours, according to a study of nearly 7,000 Japanese volunteers, although it’s not clear what this suggests about vulnerability to disturbance. It makes me feel better to know this: I need a lot of sleep!
What if you are sensitive to noise, a condition called hyperacusis?
It makes sense to explore whether noise is affecting your own sleep, but there’s scant science to help you, Clarke explains.
Get checked for sleep apnea—even if you don’t snore
If you often wake up unrefreshed, it’s a good idea to get checked for sleep apnea—a breathing problem. People with sleep apnea struggle to breathe while asleep and experience “mini-awakenings” they don’t consciously notice. Sleep apnea may contribute to hearing loss. One large study found a direct relationship: The more often your rest was interrupted by sleep apnea, the worse your hearing. This was true for both high-frequency and low-frequency hearing loss and even if you didn’t snore. Also, a small study showed that bed partners of snorers had a higher risk of noise-induced hearing loss, as well.
So is a noise machine a good idea?
It’s worth a try. Among recent studies, one found that white noise didn't help young people sleep, but another concluded that it helped hospital patients and a third that it helped people with insomnia get to sleep.
A whirring fan, hissing radiator or humming air conditioner count as white noise. You might prefer pink noise, which we hear as even rather than as staticky. Rustling leaves, steady rain, wind, and heart beats are pink. In one study, pink noise increased deep sleep and dramatically improved memory in older adults.
Earplugs, headphones and more
Price range varies widely. For under $20, you can get a CozyPhones headband, but it’s wired. The Shure SE215-K costs $100. At $200, there’s QuietOn Sleep earbuds, with a 14-day return period. And very affordable and simple foam drugstore earplugs work well for many people; women should be aware the smaller ones are likely more comfortable (often sold in pink color). They cost about $4.