Study: Pink Noise Cuts REM Sleep, Fails to Block Disruptions

A new study from researchers at the University of Pennsylvania Perelman School of Medicine has found that pink noise, a popular sleep aid mimicking sounds like rainfall or ocean waves, can reduce restorative REM sleep and fail to protect against environmental noise disruptions. The research, published in the journal Sleep, challenges the widespread use of such broadband noises among millions of people seeking better rest.

The study involved 25 healthy adults ages 21 to 41, none of whom regularly used noise machines or had sleep disorders. Over seven nights in a sleep laboratory, participants underwent eight-hour sleep sessions under varying conditions: quiet baseline, aircraft noise alone, pink noise alone at 50 decibels, aircraft noise combined with pink noise at 40 or 50 decibels, and aircraft noise with earplugs. Each morning, they completed surveys on sleep quality, alertness, and interruptions, while objective data tracked sleep stages via polysomnography.

Aircraft noise alone cut deep N3 sleep, the most restorative phase for physical recovery and toxin clearance, by about 23 minutes per night compared to quiet conditions. Participants reported lighter, more fragmented...