Pink noise reduces REM sleep and may harm sleep quality
Penn Medicine researchers find that earplugs work better in protecting sleep from traffic noise, challenging the widespread use of ambient sound machines and apps marketed as sleep aids.
2 min. read
Pink noise—a continuous sound spread across a wide range of frequencies often used to promote sleep—may reduce restorative REM sleep and interfere with sleep recovery. In contrast, earplugs were found to be significantly more effective in protecting sleep against traffic noise, according to a new study published in the journal Sleepfrom the Perelman School of Medicine.
The findings challenge the widespread use of ambient sound machines and apps marketed as sleep aids.
“REM sleep is important for memory consolidation, emotional regulation and brain development, so our findings suggest that playing pink noise and other types of broadband noise during sleep could be harmful—especially for children whose brains are still developing and who spend much more time in REM sleep than adults,” says study lead author Mathias Basner, professor of sleep and chronobiology in psychiatry.
In a sleep laboratory during eight-hour sleep opportunities over seven consecutive nights, the participants’ exposure to aircraft noise—compared to none—was associated with about 23 fewer minutes per night spent in N3, the deepest sleep stage. Earplugs prevented this drop in deep sleep to a large extent. Pink noise alone at 50 decibels (often compared to the sound of a “moderate rainfall”) was associated with a nearly 19-minute decrease in REM sleep.
If pink noise was combined with aircraft noise, both deep sleep and REM sleep were significantly shorter compared to noise-free control nights, and time spent awake was now also 15 minutes longer, which had not been observed in aircraft noise-only or pink noise-only nights.
Participants also reported that their sleep felt lighter, they woke up more frequently, and their overall sleep quality was worse when exposed to aircraft noise or pink noise, compared to nights without noise—unless they used earplugs.
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