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Why Does White Noise Help People Sleep?

A white noise machine is the simplest solution to blocking out noise.

On its face, flipping on white noise before hitting the sack must be the most counterintuitive idea out there. Want to sleep better?

Simple solution: make a bunch of noise. Sweet dreams.

Despite this, not only do some individuals claim they can't sleep without a fan going, but there are also brands and products that will offer you tailored noise-makers to help you get the most out of your slumber. What's the deal with our brains and ears?

The quick answer is that white noise is preferable than black noise. At the very least for (some) sleepers.

If you use the technical definition, white noise is a continuous noise that spreads uniformly over all audible frequencies. Assume you're a musician. To play a middle C note, you need to use a frequency of around 261.6 hertz. White noise is just an equal quantity of every frequency that a human can hear, from low to high. To continue the musical analogy, it's a massive band, each member playing a little different note. (Machines pushed to their limits, such as fans, are particularly adept at reaching these notes.)


When a noise wakes you up in the middle of the night, it is the rapid shift or inconsistencies in the sounds that startle you. White noise has a masking effect, filtering out the abrupt variations that irritate light sleepers or individuals attempting to fall asleep.

“The short version is that hearing continues to function when you are sleeping,” explains Seth S. Horowitz, a neuroscientist and author of The Universal Sense: How Hearing Shapes the Mind.

This is why the majority of bedpartners prefer the constant white noise rather than their spouse’s snoring sounds


Makes sense, right? But it’s not always that straightforward. For starters, there's pink noise. Pink noise is white noise with the higher frequencies lowered down in strength. There is some semi-complicated math involved, but in essence, pink noise is white noise with the higher frequencies set down in intensity. Pink noise is louder and more powerful in the lower end of the sound spectrum than white noise, which has the same power throughout all frequencies.


This might be beneficial for those who suffer from tinnitus or find the upper registers of genuine white noise uncomfortable. The noise family tree does not end there: depending on which frequencies you tone down or up, you may also generate Brown noise, violet noise (named for a person, not a color), and a slew of other hues. Different folks might prefer different sounds.


And, of course, not everyone requires that level of loudness. According to Horowitz, the masking effect of white noise might have the reverse effect on certain persons, actually boosting sensitivity to underlying noises. People are occasionally able to pick up noises "masked" with white noise better than they are at picking up noise in utter quiet in the odd, not-completely-explained realm of stochastic resonance.


That, however, is a topic for another essay. You appear to be exhausted. So here's the link for a good night sleep. Have some Noise!