Do you think a sound machine helps you sleep? It turns out it might not be as beneficial as previously thought. A new study from the Perelman School of Medicine at the University of Pennsylvania suggests that listening to pink noise while asleep can actually interfere with REM sleep, which is the stage associated with dreaming and essential for recovery. The findings were published in the journal Sleep, and they indicate that using earplugs can be more effective at blocking out distracting sounds, such as traffic noise.
In this study, researchers monitored 25 healthy adults, aged between 21 and 41, who had never used noise to assist with their sleep and reported no sleep issues. During an eight-hour laboratory simulation over seven nights, participants were exposed to various sounds, including aircraft noise, pink noise, a combination of both, and aircraft noise while wearing earplugs. They completed tests and surveys each morning to assess their sleep quality, alertness, and other health effects.
Interestingly, the study found that exposure to aircraft noise alone reduced the time spent in deep sleep by about 23 minutes compared to nights without any noise. However, using earplugs significantly mitigated this effect. When participants were subjected to pink noise at 50 decibels—akin to light rainfall—they experienced nearly 19 fewer minutes of REM sleep. The combination of aircraft noise and pink noise resulted in significant reductions in both REM and deep sleep, along with an increase in waking time.
Participants reported that their sleep felt “light” and of overall poor quality, waking more frequently when exposed to aircraft or pink noise unless they used earplugs. Dr. Matthias Basner, the study’s lead author, emphasized the importance of REM sleep for memory consolidation and emotional regulation. He noted that while incidental sounds might be meant to help, they can actually be harmful to children who require more REM sleep for brain development.
Though pink noise has some positive effects, like lowering fragmentation caused by environmental noise, Basner suggested that its continuous stimulation could pose risks, particularly for vulnerable populations like infants. Experts have often touted sound machines as helpful for sleep, but this study suggests a need to reconsider that stance.
Dr. William Lu, a sleep specialist, remarked that while pink noise could mask disturbances, it ultimately might require the brain’s attention, potentially sacrificing REM sleep without us realizing. He highlighted that different types of noise impact sleep differently and that pink noise specifically might fragment REM sleep.
With all this in mind, the researchers concluded that more comprehensive studies are needed to understand the long-term effects of pink noise and other sleep aids. They warned that using broadband noise, particularly for young children, requires careful consideration regarding safe sound levels and the potential for adverse effects. Until more is known, if someone still wishes to use pink noise, it’s advisable to keep the volume low and set timers to lessen continuous exposure.
In short, while sound machines may be well-intentioned for improving sleep, their actual efficacy—and safety, particularly for kids—remains in question.
