Pink Noise May Disrupt Sleep, Study Finds * Science and Technology Times

A new study suggests that pink noise, often promoted as a calming sleep aid, may actually reduce sleep quality.
Researchers observed measurable declines in REM and deep sleep when participants were exposed to pink noise or environmental noise.
The findings raise questions about the safety of broadband noise for sleep, especially for children and other vulnerable groups.

A Popular Sleep Aid Under Scrutiny

Pink noise has long been marketed as a gentle alternative to white noise, offering a softer, rain‑like sound profile. Many apps and devices promote it as a tool for masking environmental disturbances and improving sleep. A new study led by researchers at the University of Pennsylvania, with collaborators in Europe and Canada, challenges this assumption. Their findings indicate that pink noise may reduce the amount of restorative sleep rather than enhance it.

Broadband noise refers to continuous sound spread across a wide range of frequencies. White noise is the most familiar example, though brown, blue, and pink noise each differ in how sound intensity is distributed. Earlier research on white noise has produced mixed results, suggesting potential benefits but also raising concerns. Pink noise, with its emphasis on lower frequencies, has been perceived as more soothing, yet the new data complicates that narrative.

The study recruited 25 adults aged 21 to 41 who had no sleep disorders and did not regularly use noise for sleep. Participants spent seven consecutive nights in a sleep laboratory, attempting to sleep for eight hours under varying sound conditions. After an initial quiet night to acclimate, each subsequent night introduced a different auditory environment. The order of these conditions varied between groups to avoid bias.

Participants encountered several scenarios, including environmental noise, pink noise alone, and combinations of both. Environmental noise included aircraft, vehicles, and a crying baby, representing common nighttime disturbances. Other nights served as quiet controls or involved earplugs to reduce exposure. Surveys, cognitive tests, cardiovascular measurements, and sleep‑stage data provided a comprehensive picture of sleep quality.

Pink Noise Reduced REM Sleep in Controlled Tests

Compared with quiet nights, environmental noise reduced time spent in N3 sleep—the deepest sleep stage—by an average of 23 minutes. Pink noise alone at 50 decibels was linked to nearly 19 fewer minutes of REM sleep per night compared to environmental noise. Nights combining environmental and pink noise showed the most pronounced effects, with significant reductions in both REM and deep sleep. Participants also spent more time awake during these combined‑noise nights, a pattern not observed with either sound alone.

Overall sleep quality declined on nights with noise exposure, including those with pink noise. Earplugs, however, appeared to mitigate these effects, as participants wearing them did not show the same reductions in sleep stages. This suggests that passive noise blocking may be safer than adding broadband noise to the environment. The researchers emphasize that even small reductions in REM or deep sleep can have meaningful consequences for health.

REM sleep plays a critical role in memory consolidation, emotional regulation, and brain development. University of Pennsylvania sleep researcher Mathias Basner notes that children, who spend more time in REM sleep, may be particularly vulnerable. The findings therefore raise concerns about using pink noise in nurseries or for toddlers. While many people rely on broadband noise to sleep, the evidence remains inconclusive and warrants caution.

Millions of individuals use noise‑based sleep aids, yet the long‑term effects remain poorly understood. The study highlights the need for more research on different types of broadband noise and their impact on sleep architecture. Vulnerable populations, such as infants and older adults, may require special attention. Safe volume levels and exposure durations also need clearer guidelines.

Implications for Sleep Health and Future Research

The researchers argue that broadband noise should not be assumed harmless simply because it masks external sounds. Their results suggest that the brain continues to process these noises during sleep, potentially disrupting essential sleep stages. Earplugs may offer a more reliable way to reduce environmental disturbances without introducing new auditory stimuli. This approach could help preserve REM and deep sleep, which are vital for cognitive and physical health.

The study’s small sample size means the findings should be interpreted cautiously, yet they align with earlier concerns about noise exposure during sleep. Larger studies could help determine whether certain frequencies or volumes are safer than others. Understanding individual differences may also be important, as some people report subjective benefits from noise despite measurable disruptions. Future research may explore whether adaptive or dynamic soundscapes offer better outcomes.

Broadband noise remains widely used despite limited scientific consensus. Many sleep apps and devices promote pink noise as a natural, calming solution, but the new data suggests a more nuanced picture. Users may need to balance perceived comfort with potential physiological effects. The researchers recommend avoiding broadband noise for newborns and toddlers until more evidence is available.

Sleep hygiene practices such as maintaining a dark, quiet environment and reducing screen time remain well‑supported by research. Noise‑masking technologies may still have a role, but their use should be informed by emerging evidence. As sleep science evolves, consumers may benefit from more personalized recommendations. The study underscores the importance of understanding how auditory environments shape sleep quality.