Pink noise reduces REM sleep and may harm sleep quality

Researchers observed 25 healthy adults, ages 21 to 41, in a sleep laboratory during eight-hour sleep opportunities over seven consecutive nights.

Absurdly low n. Additionally, I've become very skeptical of anything coming out of sleep labs after my wife was sent to one (at a prestigious teaching hospital) by her doctor some years ago: the 'sleep opportunity' was lights out at 9pm for 8 hours, and the staff were wholly indifferent to the fact that she's a night owl and prefers to sleep after midnight. Additionally she reported that it was not particularly quiet or dark.

I am not a fan of noise machines but I have noticed that I sleep best on rainy nights, which has a similar average sound spectrum, and is about the same as the sound of your blood circulating near your eardrums. Testing pink noise along with aircraft noise (which is closer to red noise) is equivalent to just making the noise level higher with slightly more midrange energy. Some noise can be relaxing for light sleepers; too much is just annoying.

My ex-partner has tinnitus and saw a psychologist who specialised in tinnitus. The psychologist suggested she buy a machine that generates a sound slightly quieter than her tinnitus which retrains the brain not to hear the tinnitus. So she bought a machine that generated about 15 different sounds and settled on a pink-ish sound and played while she slept. It took a couple of years but it effectively "cured" her tinnitus. It drove me mad for a while but after a while I didn't notice it.

The machine had different sounds because the sound of tinnitus is different for different people: hers sounded like cicadas, a sound I quite like but she hates!

I have misophonia and used to live in a house where a coffee van would start a generator at 0530 so I used a fan to help drown out the sound. I could still hear the generator but I could sleep through. It fundamentally changed the quality of my life.

Only tangentially related.

I occasionally fall asleep to either a movie / TV episode on repeat in a media player on the PC in my bedroom, or a YouTube short which repeats.

The audio almost always gets integrated in to my dreams, and almost always in a highly entertaining and humours way.

Anyways, I feel I sleep better when there is background sound, even if it’s other people (quietly) partying in the house.

A lot of comments here dismiss the study for having a small N.

Exploratory research uses small N at the start. This kind of research can have value even if it is not conclusive.

Imagine the expense (and dominance of Big Research) if every study needed 100,000 participants to run.

If you don’t want to read exploratory studies, ignore them when they hit the headline news.

Other criticisms of this study (e.g., participants didn’t previously sleep with noise) seem more on the mark. I’m not an uncritical fan.

I have the best. Natural noise generator, which means microphones outside. With 3 layered windows the winter is just too silent, or rather: filled annoying multistory house noises. In summertime windows are open and that is about the suitable noise level.

Also there is the outdoorsman's reaction to silence. When birds go silent, there is something bad happening. Bears or wolf pack.

"Pink noise sounds like a waterfall." https://en.wikipedia.org/wiki/Pink_noise

I would recommend reading the paper rather than the article, or at least the abstract:

> Compared to a noise-free control night, EN reduced N3 deep sleep (p < .0001) while PN reduced REM sleep (p < .001). Adding PN to EN worsened sleep structure, despite minor dose-dependent improvements of EN-induced sleep fragmentation and N3 sleep increases. Earplugs mitigated nearly all EN effects on sleep but started failing at the highest EN level (65 dBA). Morning cognition, cardiovascular measures, and hearing were not affected by nighttime noise, but subjective assessments of sleep, alertness and mood were significantly worse after EN and PN exposure.

I grew up in South East Asia with air con running all night, when I moved away I found it hard to sleep in 'quieter' countries

I feel unsafe wearing earplugs. You're so totally unaware. I'm worried I'd sleep through an alarm.

This study had no controls at all, and can safely be ignored.

>The participants reported not previously using noise to help them sleep or having any sleep disorders.

All this study said was that people who didn't need noise to sleep had their sleep disrupted when noise was introduced. It has absolutely no implication for people who use noise to help them sleep.

Meaningless trash.

study aside, pink noise is awful imo - it's perfect if you're calibrating a PA system and need specific power spectral density properties, but bad for my brain. if sleeping somewhere without a fan or whatever i use brown noise, it's closer to a lower rumbling.

Thanks for sharing. I'll have to reconsider my nightly noise setup, but good to know.

7 nights is not nearly enough to get used to new environmental factor introduced in the study, possibly exacerbating disruption from sleeping in a new place (sleep clinic).

n=25? Seriously?

This is barely passable as an early hypothesis test before you perform an actual study.

> 25 healthy adults

Come on guys. Replication crisis has been fully documented

I get how difficult a study like this is to carry out, but each participant was involved for just seven days, each night exposed to different conditions. The control environment was silence, and every other conditions did worse than controlled silence. In others they piped in fake environmental noises, pink noise, or made the participants wear earplugs with some other combination.

Eh. People condition to an environment, and someone conditioned to something like pink noise wouldn't have the acclimation issue (and they either specifically selected for people who don't use noise machines, or they just randomly got only people who don't), and it might drown out smaller environmental noises that otherwise would have disrupted their sleep. It would take a much longer study to determine this.

Or hey, maybe those insecure sleep masks tracking EEG and other things will give us some insights eventually. People just need to harvest the data from the other services.

> Participants slept under different conditions, including being exposed to aircraft noise, pink noise, aircraft noise with pink noise and aircraft noise with earplugs

And yet the conclusion is about pink noise vs silence. We may have a new textbook example of HARKing right here!