Noises for Sleep 

According to the Centers for Disease Control and Prevention (CDC), 30 percent of American adults are suffering insufficient sleep every night.Lack of sleep can immediately lower your work and study efficiency and over time do harm to both physical and mental health of adults and children. That’s why for a long time people are seeking help in many ways. Using noises during sleep is one of them.The most commonly used sleep noises include white noise, pink noise and brown noise. But what are they? What are the differences among them? And how can they help sleep? Keep reading to understand. 

White Noise

Different from the ambient sounds of rainstorms, chirping birds, and rolling waves, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. Technically, it remains consistent across all audible frequencies. That consistency blocks out the sudden changes in noise, like the aforementioned snoring, or the dog barking, or a truck rumbling down the street, which can wake you up during the night. White noise is sometimes also referred to as a broadband noise.So the common white noises may include:

  • whirring fan
  • radio or television static
  • hissing radiator
  • humming air conditioner

Researchers have studied the effect of white noise to sleep for many years. In a study related to sleep of patients admitted to a coronary care, 62 patients were divided into 2 groups, with one exposed to white noise during sleep and the other not. The result shows that the patients who listened to white noise while sleeping had more sleep with higher quality than those who didn’t. Thus, the researchers concluded that “the use of white noise is recommended as a method for masking environmental noises, improving sleep, and maintaining sleep in the coronary care unit.”Another experiment studied 18 healthy subjects suffering from insomnia by exposing them in random order to normal environmental noise (40.1 [1.3] dB) or to broadband sound administration, the result shows that broadband sound administration significantly reduced sleep onset latency by 38% compared to normal environmental noise, suggesting that broadband sound administration might be helpful to minimize insomnia symptoms in selected individuals. 

Pink Noise

The color of noise differs as the energy of sound signal differs. Or, it depends on how energy is distributed over various frequencies, or the speed of sound. Pink noise is a kind of white noise, but with reduced higher frequencies. It  is often considered to be more soothing than white noise as people don’t fine as much unpleasant as in the latter.Pink noise is always associated with nature:

  • rustling leaves
  • steady rain
  • wind
  • heartbeats

Pink noise can be sleep-inducing. A 2012 experiment studied 50 subjects by  letting them experience two consecutive sleeps, of which one was pink noise exposed and the other was not, and analyzed the electrocardiography (ECG) signal with cardiopulmonary coupling approach. The result demonstrates that “steady pink noise has significant effect on reducing brain wave complexity and inducing more stable sleep time to improve sleep quality of individuals.”Besides, pink noise could also contribute to deep sleep which supports memory and helps you feel refreshed in the morning. 

Brown Noise

Brown noise(also called red noise) gets its name from Robert Brown, a botanist who first discovered "Brownian motion," aka random particle motion,  lowers the higher frequencies even more than pink noise. So it sounds deeper than white noise and pink noise.You may usually find brown noise in:

  • low roaring
  • strong waterfalls
  • Thunder

Brown noise may help with getting a good night’s sleep, but it can also help with focus and concentration. Many people prefer listening to brown noise when studying or working to improve productivity and drown out any distractions. It can also help ease anxiety, especially in high-stress situations. 

Other Colors of Noise

Blue noise contains all the audible frequencies, but opposed to white noise, it amplified the higher-pitched frequencies. Because of this, blue noise can sound harsh to some people and isn’t widely used for sleep support, but audio engineers often use blue noise for dithering, a process where they intentionally add noise to a production, such as a song remix, in order to smooth out the sound. An example of this type of noise would be a hissing hose.
Black noise uses pure silence with sudden occurrences of noise. The dominant energy level is zero throughout all frequencies with bits of random noise and occasional rises.