Sleeping with Sound: When a Little Noise Might Be Good for You
The stimulating noises of daily living aren’t the sounds we typically want to take with us to bed, as they can make for a frustrating night of interrupted sleep. But can sleeping with a little noise actually help you wake up more refreshed? Some researchers say yes, depending on the sound. And with 1 in 3 adults suffering from lack of sleep, listening to the sound of particular colors may provide comforting relief. Yes — you heard right. Colors have sound, and they are referred to as sonic hues. The color of noise you listen to at night can improve your sleep.
Let’s take a closer look at this unique facet of sleep health.
Sounds to Help You Sleep
Causes of sleeplessness may include poor sleeping habits due to shift work, stress, aging, too much stimulation before bed, and noisy environments. While it may seem counterintuitive to use noise to drown out disturbing sounds, researchers say it might promote deep sleep and better memory. White noise machines have gained popularity for this reason, but there is an entire gamut of colors that produce subtly different sounds. Here are the most commonly used ones, as well as real-life examples.
1. White Noise
Humans can hear frequencies within the audible sound range from 20Hz to 20,000Hz — about 10 octaves — which means the sound pressure in your ear vibrates back and forth between 20 to 20,000 times per second. White noise is the sound of all individual frequencies in the audible range playing at once, similar to how the color we perceive as white is actually all the colors in the visible light spectrum. Light entering a prism at an angle displays this when it bends the light, scattering the waves into a rainbow. Simply put, the color we perceive as white is not just light — it is all the colors of the rainbow in the visible light spectrum.
It's no wonder, then, that white noise sounds like a high-pitched static, similar to what you may hear on an unused radio station or TV channel. Some people don't realize they use white noise for better sleep when they run a fan or air conditioner. One study monitoring the effects of white noise on ICU patients found that it improved sleep quality by reducing the arousal of high-peak noise in the busy hospital.
2. Pink Noise
Pink noise sounds softer compared to white noise because more power is held in the low-frequency range (near red) on the light spectrum. If white noise is how a computer hears each frequency, pink noise is how humans perceive those individual frequencies — in octaves. Human ears are octave-friendly, making pink noise more pleasing to listen to — think crashing waves or gentle rain.
Researchers studied pink noise to determine if it could promote longer periods of slow-wave activity (SWA) — a measurement of deep sleep, or slow-wave sleep (SWS) — in older adults. When pink noise was pulsed at different intervals through the night, participants’ word recall significantly improved overnight as SWA increased — supporting the sleep-dependent memory retention for adults over 60. Interestingly, findings from 2013 had already shown that pink noise could improve memory capacity in younger subjects, too.
3. Brown (Red) Noise
Brown noise, also called red noise, is an even deeper form of pink noise. Why is it named “brown?” It was named after botanist Robert Brown who discovered the noise of random particle motion — also known as Brownian motion. The power of brown noise is concentrated in the lower frequencies of the red end of the light spectrum, giving a deep, rumbling sound. If you have been to a heavy waterfall or listened to thunder, you’ve heard brown noise. To date, research about how brown noise can help you sleep better is lacking. However, if you like falling asleep listening to thunder or roaring waters, you may enjoy falling asleep to brown noise.
4. Black Noise
Colors are what we see when light reflects off 3D objects and into our eyes, making the objects visible and able to be interpreted by our brains. When there is a lack of light, there is a lack of visible color spectrum. Black, then, is the absence of color, making black noise the absence of sound — silence. Silence is hard to come by in everyday life, as there is usually some amount of subtle noise almost everywhere we go. Many feel more relaxed in silence, though, making sleeping easier and more rejuvenating. If you need silence to help you sleep, it might be time to pop in some earplugs or noise-canceling headphones to drown out the nighttime sounds.
White and pink noise — the most studied of all sonic hues — offer the possibility of the deep sleep necessary for supporting larger memory storage and recall ability. Brown noise is another popular choice that many use to promote healthy sleep due to its deep, low-frequency bass tone.
As we all have individual hearing curves, certain noises may sound different to each of us. Try sampling various noises to see which sound feels most relaxing to you. Online sites like YouTube have numerous free videos, or you might consider purchasing a noise machine. Phone apps may also be an option — offering an array of sonic hues to choose from that may help you get deeper, regenerative sleep.
1 in 3 adults don't get enough sleep. (2016, February 16). Retrieved from https://www.cdc.gov/media/releases/2016/p0215-enough-sleep.html
Brains of deaf people rewire to 'hear' music. (2001). Retrieved from https://www.washington.edu/news/2001/11/27/brains-of-deaf-people-rewire-to-hear-music/
Color and Sound: Physical and Psychophysical Relations. (n.d.). Retrieved from (PDF)
Electromagnetic Spectrum. (n.d.). Retrieved from https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html
Ngo, H., Martinetz, T., Born, J., & Mölle, M. (2013). Auditory Closed-Loop Stimulation of the Sleep Slow Oscillation Enhances Memory. Neuron, 78(3), 545-553. doi:10.1016/j.neuron.2013.03.006
Papalambros, N. A., Santostasi, G., Malkani, R. G., Braun, R., Weintraub, S., Paller, K. A., & Zee, P. C. (2017). Acoustic Enhancement of Sleep Slow Oscillations and Concomitant Memory Improvement in Older Adults. Frontiers in Human Neuroscience, 11. doi:10.3389/fnhum.2017.00109
Roth T. Slow wave sleep: does it matter?. J Clin Sleep Med. 2009;5(2 Suppl):S4-S5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824210/
The Science of Sound. (n.d.). Retrieved from https://www.nasa.gov/specials/X59/science-of-sound.html
Sleep Deprivation and Deficiency. (n.d.). Retrieved from https://www.nhlbi.nih.gov/health-topics/sleep-deprivation-and-deficiency
Stanchina ML, Abu-Hijleh M, Chaudhry BK, Carlisle CC, Millman RP. The influence of white noise on sleep in subjects exposed to ICU noise. Sleep Medicine. 2005;6(5):423–8.