For a lot of people, silence isn’t actually relaxing. It leaves too much room for thoughts to wander or spiral into “why am I still awake?” territory, which is why some sounds make it easier to switch off.
But does listening to sounds actually improve your sleep? And does the type of sound matter? Let’s find out.
Most Common Sounds Used for Falling Asleep
White Noise
White noise is the most commonly used sleep sound. It covers a wide range of frequencies played at the same intensity, which is why it comes across as a steady, uniform hum.
Some studies have found it can help people fall asleep faster and wake up less during the night. In certain cases, it’s also been linked to slower heart rate and breathing.
Pink Noise
Pink noise contains the same range of frequencies as white noise, but the higher ones are quieter, which gives it a softer, more natural quality, closer to things like rainfall or ocean waves.
Scientific research shows that continuous pink noise is not beneficial for sleep. In one controlled study, pink noise at around 50 decibels reduced REM sleep by nearly 19 minutes per night.
The study itself was fairly controlled. Researchers at the University of Pennsylvania observed 25 healthy adults over seven consecutive nights in a sleep lab, giving them full 8-hour sleep opportunities under different conditions, including silence, environmental noise, pink noise, and combinations of both.
What they found was that participants exposed to pink noise reported lighter sleep, woke up more often, and felt worse rested in the morning compared to quiet nights.
When pink noise was combined with real-world noise, like aircraft sound, the effects were stronger. Both REM and deep sleep were reduced, and participants spent about 15 minutes longer awake during the night.
Brown Noise
The popularity of brown noise for sleep has grown significantly in recent years, largely driven by communities of people with ADHD who report that it quiets mental chatter in a way other sounds do not.
Brown noise has higher intensity at lower frequencies even more so than white and pink noise, and decreases in intensity by about 6 decibels per octave, resulting in a deeper sound.
Scientific research on brown noise specifically for sleep remains insufficient to draw definitive conclusions, with its effectiveness supported primarily by personal testimonials rather than controlled research.
The studies that do exist tend to extrapolate from white noise findings and assume similar mechanisms, which may or may not be accurate.
What brown noise has going for it is that the risk profile looks lower than pink noise, the volume required to achieve a masking effect tends to be lower, and for people who find white noise too harsh, it offers a more comfortable alternative with a similar functional mechanism.
If it works for you, there is currently nothing in the research suggesting you should stop.
Nature Sounds
A lot of us like falling asleep to the soothing sounds of rain, waves, or a distant thunderstorm. These sounds feel familiar and easy to settle into, which makes them less distracting than artificial noise.
A 2017 Sussex University study using MRI scanners found that natural sounds had the greatest effect on the autonomic nervous systems of participants, shifting them away from the fight-or-flight response and toward the rest-and-digest state that precedes sleep.
Unlike synthetic noise colours, nature sounds carry an additional layer of psychological familiarity that may make them easier to relax into, even for people who find other frequencies uncomfortable.
ASMR
ASMR refers to a category of sounds and videos designed to trigger a calming, almost hypnotic response.
ASMR is commonly used as a sleep aid, especially among younger generations, because of how soothing and repetitive the sounds can be. These can range from whispering and soft speaking to tapping, scratching, brushing, or slow, deliberate movements.
There isn’t much solid research on its effects on sleep, but a lot of people find it helps them relax and drift off more easily.
Music
Music has been used as a sleep aid for centuries – historical records show that King Louis XIV had musicians play softly in their chambers to help him relax and fall asleep.
Listening to music decreases levels of cortisol, the stress hormone that keeps you alert, and can reduce anxiety, blood pressure, heart rate, and respiratory rate.
Across studies, music consistently reduced the time it took to fall asleep, improved sleep efficiency, and increased total sleep time, with the most effective music being slow in tempo, between 60 and 80 beats per minute.
How Scent Influences Sleep
Even when you’re asleep, your brain doesn’t fully switch off. It keeps processing what’s happening around you, especially sound and smell. That’s why background noise can affect your sleep, and the same applies to scent, with the only difference being how it’s processed.
Smell goes through the olfactory system, which is directly connected to areas of the brain involved in emotion, memory, and automatic responses. It doesn’t need the same level of conscious attention.
Because of that, scent can influence how the body responds without pulling you out of sleep. Instead of something your brain listens to or follows, it works more in the background, nudging things like relaxation and sleep depth without becoming distracting.
Kimba is a sleep device that uses scent in a controlled, responsive way rather than just diffusing it constantly into the room. It combines built-in sensors with data from wearable devices to track your sleep patterns in real time.
Based on that, it detects where you are in your sleep cycle, whether you’re falling asleep, in lighter sleep, or not staying in deeper stages, and adjusts accordingly. Instead of running continuously, it releases small, timed bursts of scent when they’re most likely to have an effect.
The idea is to support sleep at the points where it actually needs support, rather than adding a constant stimulus throughout the night.
That way, it can help you fall asleep and stay in deeper sleep without introducing something your brain has to keep processing the entire time.
Sources:
Can white noise really help you sleep better? – Harvard Health
https://www.health.harvard.edu/staying-healthy/can-white-noise-really-help-you-sleep-better
Pink noise sleep study – University of Pennsylvania
https://www.pennmedicine.org/news/news-releases/2026/pink-noise-sleep-study
Natural sounds and relaxation – Scientific Reports
https://www.nature.com/articles/s41598-017-xxxx
Music and sleep quality – Frontiers in Psychology
https://www.frontiersin.org/articles/10.3389/fpsyg.2018.00264
Music for insomnia review – Sleep Medicine Reviews
https://www.sciencedirect.com/science/article/pii/S1087079215000629
White noise and sleep – PubMed
https://pubmed.ncbi.nlm.nih.gov/17346996/
White noise volume safety – McGill University
https://www.mcgill.ca/oss/article/health/how-loud-too-loud-white-noise
Auditory stimulation reviews – Sleep Medicine Reviews
https://www.sciencedirect.com/journal/sleep-medicine-reviews
