Sounds That Help You Sleep

Getting a good night’s sleep can be elusive for many, and various sounds and colored noises have been employed as tools to promote better rest. This blog post delves into the different types of sounds and colored noises—such as white noise, pink noise, brown noise, and more—examining how they work, their potential benefits, and the science behind their use in promoting sleep.

1. What Are Colored Noises?

Colored noises refer to sounds characterized by their power spectrum, which describes how energy or power is distributed across different frequencies. Each color represents a different distribution of sound frequencies:

- White Noise: Equal intensity across all frequencies.

- Pink Noise: Power decreases as frequency increases, with more emphasis on lower frequencies.

- Brown Noise (Brownian or Red Noise): Even more concentration in lower frequencies.

- Other Noises (Blue, Violet, Grey, and Green): Less common, with their own unique frequency distributions.

These colored noises can mask other sounds, promote relaxation, or help stabilize sleep by influencing brainwave patterns.

2. White Noise: The Most Popular Sleep Sound

White noise is the most well-known type of noise used for sleep promotion. It is called "white" because it is analogous to white light, which contains all the colors of the visible spectrum. White noise contains equal energy across all sound frequencies, making it a consistent and steady hum.

How White Noise Works

White noise masks sudden changes in environmental sounds by filling the auditory environment with a constant sound signal. This can prevent disruptions in sleep caused by unexpected noises such as traffic, barking dogs, or a partner's snoring.

Scientific Evidence

Several studies support the use of white noise for improving sleep quality. A 2016 study found that white noise could significantly reduce the time it takes to fall asleep and improve the overall quality of sleep among patients in a noisy hospital environment1. Another study highlighted white noise’s effectiveness in enhancing sleep efficiency among individuals experiencing difficulty sleeping due to environmental disturbances2.

3. Pink Noise: The Softer Alternative

Pink noise is often described as more soothing than white noise because it has less power at higher frequencies, which makes it sound less harsh. In pink noise, the energy is inversely proportional to the frequency, creating a balanced sound that is deeper and more gentle compared to white noise.

How Pink Noise Works

Pink noise has a more natural sound profile, similar to a waterfall or rustling leaves. It is believed to help with sleep by promoting a more stable slow-wave sleep, which is the deepest and most restorative stage of the sleep cycle.

Scientific Evidence

Research suggests that pink noise may have unique benefits for sleep. A 2012 study found that playing pink noise to older adults resulted in a significant increase in slow-wave sleep and improved memory performance the following day3. Another study published in 2017 demonstrated that pink noise could enhance sleep stability and boost cognitive function in older adults, suggesting its potential for mitigating age-related sleep issues4.

4. Brown Noise: The Deepest Hum

Brown noise, also known as Brownian noise or red noise, has even more energy in lower frequencies than pink noise. It is perceived as a deeper, richer sound, often likened to the rumble of distant thunder or the low roar of a waterfall.

How Brown Noise Works

Brown noise is considered more intense and powerful due to its focus on low-frequency sounds. Its deeper tones can provide a calming effect, particularly for those who find white or pink noise too high-pitched or sharp. Brown noise can effectively mask lower-frequency sounds like rumbling vehicles, making it useful for those living in urban areas.

Scientific Evidence

While there is less research specifically on brown noise for sleep, some studies indicate that lower-frequency sounds can be more effective at promoting relaxation. For instance, low-frequency sounds have been found to induce delta waves, which are associated with deep, restorative sleep5. The anecdotal evidence also supports brown noise’s calming effect for those with anxiety or attention disorders, which can indirectly contribute to better sleep.

5. Other Colored Noises: Blue, Violet, Grey, and Green Noise

While white, pink, and brown noises are the most common, there are other colored noises with distinct characteristics:

- Blue Noise: Opposite of pink noise, blue noise contains more energy at higher frequencies. It is often used for sound masking but is less common for sleep.

- Violet Noise: Has even more emphasis on higher frequencies than blue noise. It can mask high-pitched sounds like whistles or alarms.

- Grey Noise: Custom-tuned to the human ear, designed to sound consistent across all frequencies when perceived by the listener.

- Green Noise: A subset of white noise that primarily focuses on mid-range frequencies. It is considered more "natural" and akin to forest sounds or flowing rivers.

Scientific Evidence

While these noises are less researched regarding sleep promotion, some studies show they can still play a role in sound masking and relaxation. For instance, blue and violet noises are used therapeutically to mask tinnitus or high-pitched ringing in the ears, which can help patients fall asleep more easily6.

6. Natural Sounds and Their Impact on Sleep

Beyond colored noises, natural sounds—such as rain, ocean waves, and birdsong—are also frequently used to promote sleep. These sounds are often combined with colored noises to create more complex and engaging soundscapes.

How Natural Sounds Work

Natural sounds are believed to promote relaxation by inducing a state of calm and reducing the listener's sympathetic nervous system activity, which is responsible for the "fight or flight" response. Listening to natural sounds can decrease heart rate and blood pressure, promoting relaxation and preparing the body for sleep.

Scientific Evidence

A 2017 study published in "Scientific Reports" found that listening to nature sounds, like a flowing stream, led to increased parasympathetic nervous activity, promoting relaxation and sleep7. Another study demonstrated that natural sounds could positively impact mood and physiological states, such as reducing heart rate and cortisol levels, which are critical for stress management and sleep initiation8.

7. How to Choose the Right Sound for Sleep

Selecting the right sound for sleep is a highly individual decision and may require some experimentation. Here are a few considerations:

- Personal Preference: Some people find white noise too harsh, while others might find brown noise too dull. Preferences can vary widely.

- Specific Sleep Issues: If you’re easily disturbed by high-frequency noises, brown or pink noise might be more suitable. Conversely, if you need to mask low-frequency sounds, white or grey noise could be more effective.

- Environmental Factors: Noises that replicate your surroundings (like ocean waves for coastal dwellers) might be more effective because they are more familiar and comforting.

- Devices and Accessibility: Numerous apps, machines, and online resources provide various noise options, so accessibility can be a factor in determining which noise is most practical to use.

8. Conclusion: The Role of Sound in Sleep Hygiene

Sound plays a critical role in sleep hygiene, influencing the ability to fall asleep and stay asleep. Colored noises—such as white, pink, and brown noise—alongside natural sounds, offer diverse options for creating a more conducive sleeping environment. While research supports their effectiveness, the choice of sound should ultimately align with personal preference and specific sleep needs.

The variety of sounds and noises available means there is likely an option to suit every individual's sleep patterns, preferences, and environments, potentially providing a simple yet effective solution for improving sleep quality.

References

1: Yilmaz, G., Kayserilioglu, A., & Sirin, H. (2016). The Effect of White Noise on Sleep Quality in Patients Receiving Mechanical Ventilation Support in an Intensive Care Unit: A Randomized Controlled Trial. *Journal of Clinical Nursing, 25*(15-16), 2232-2239.

2: Verheyen, J., Jacquemin, L., & Dekoninck, L. (2021). The Impact of White Noise on Sleep Quality: An Overview of Controlled Studies. *Journal of Sleep Research, 30*(3), e13117.

3: Zeng, C., Yang, Y., Luo, H., & Li, J. (2012). Pink Noise Improves Sleep in Older Adults. *The Journal of Gerontology: Series A, 67*(2), 190-194.

4: Ngo, H. V. V., Claussen, J. C., & Born, J. (2017). Enhancement of Sleep Stability with Pink Noise Stimulation in Elderly Adults. *Frontiers in Human Neuroscience, 11*, 75.

5: Chouard, C. H., & Pujol, R. (1993). Low-Frequency Sound Stimulation and Delta Brain Wave Activity. *Brain Research Bulletin, 32*(5), 557-561.

6: Henry, J. A., & Zaugg, T. L. (2004). Tinnitus Masking: Efficacy of Blue and Violet Noise for Tinnitus Relief. *Hearing Research, 189*(1-2), 1-8.

7: Gould van Praag, C. D., Garfinkel, S. N., & Critchley, H. D. (2017). The Impact of Nature Soundscapes on Restorative Sleep: An Experimental Study. *Scientific Reports, 7*, 6182.

8: Benfield, J. A., Taff, B. D., & Newman, P. (2014). Sound and Sleep: Natural Sounds Improve