A recent study has revealed that while pink noise is popular for promoting better sleep, it may actually disrupt your rest, contradicting common beliefs.

Pink noise, akin to white noise, encompasses all audible frequencies but emphasizes lower frequencies. Various sounds used for brain stimulation are categorized into colors based on how their noise spectrum aligns with the spectrum of colored light. Notably, white noise plays all frequencies at equal intensity, similar to how white light combines all visible colors.

Pink noise resembles the soothing sounds of rain or ocean waves. However, findings suggest mixed effects on memory and sleep benefits.

Conducted at the University of Pennsylvania, a 7-day study evaluated sleep quality among 25 healthy adults, primarily young women, exploring the impacts of environmental noise, pink noise, and earplugs. Participants did not have any sleep disorders or frequently use sound machines.

Participants were instructed to turn off lights at 11 PM and rise at 7 AM.

During the sleeping hours, participants encountered various noise scenarios: no noise, isolated environmental noise, pink noise alone, a blend of pink and environmental noise at different volumes, or environmental noise with earplugs.

Environmental sounds ranged from traffic to sonic booms.

Sleep encompasses phases, including light eye movement, deep sleep, and REM sleep—where dreaming occurs.

Published in the journal Sleep, the study demonstrated that environmental noise notably disrupts stage 3 sleep, leading to an average reduction of 23.4 minutes in this crucial phase, which is essential for cognitive function and memory.

Moreover, pink noise was found to decrease REM sleep duration by 18.6 minutes, a vital phase for mood regulation and mental clarity.

Dr. Matthias Basner, lead author and professor of psychiatry at the University of Pennsylvania, expressed surprise at the significant disruption pink noise caused to sleep.

“While there’s existing literature on REM sleep reduction, it was overlooked until now,” he stated.

The researchers evaluated cognitive and physiological responses before and after each sleep session, alongside monitoring participants’ sleep and inquiring about their mood and fatigue levels.

Although losing 20 minutes of REM sleep may seem minor, Dr. Basner highlighted that these minutes accumulate over time.

“Losing just 10 minutes a night could total 70 minutes over a week, and over a year, that’s a significant 3,640 minutes,” he explained.

The study did not explore ambient noise impacts on infants or children. Dr. Basner cautioned that REM sleep loss may be even more critical in newborns, who spend 50% of their sleep in REM compared to only 25% for adults. He advised against using noise machines for infants and young children.

Adults typically require 7 hours of sleep each night, and each minute of lost REM sleep is significant, according to Basner.

“I won’t dismiss it as trivial; these disruptions can impact wellbeing,” he remarked.

Basner speculated that “constant auditory input” might interfere with the brain’s sleep processes, but the specific reasons why pink noise affects REM sleep remain unclear.

While pink noise aided in falling asleep amidst traffic sounds, earplugs proved more effective in blocking external noise.

The study has limitations; the small sample size of 25 adults was assessed over only seven nights. Over longer durations, participants might adapt to pink noise and revert to normal sleep patterns. Also, the environmental noise included atypical sounds like jet engines, which might also be acclimated to over time.

Noise levels fluctuated nightly, leading to inconsistent sleeping conditions. Even within a controlled lab environment, many participants had never previously slept there, possibly affecting their sleep quality.

Dr. Rafael Pelayo, a clinical professor at Stanford’s sleep medicine division, emphasized that lab study outcomes may not fully reflect typical home environments.

“Though sleep is a biological necessity, sleep habits are learned,” he remarked, suggesting that people can adapt to various sleeping circumstances, similar to managing a snoring partner.

If you find a sound machine beneficial, Dr. Basner recommends using it at a low volume and setting a timer to avoid it running all night.

“I don’t want to undermine its popularity; there may be valid reasons many individuals rely on it,” he concluded.