Forget white noise machines — brown and pink noise are trending

Many of us like to fall asleep to the sounds of a white noise machine, but according to TikTok, brown and pink noise may be the sleep aides of the future. The hashtags #brownnoise and #pinknoise have already racked up more than has over 175 million posts.

White noise is a non-specific sound often compared to static or distant rain. The new “color” sounds, on the other hand, “describe the strength and frequency of a noise signal on the power spectrum,” explained Shelby Harris, Psy.D., a clinical psychologist specializing in behavioral sleep medicine at Sleepopolis.

Brown noise contains sounds from every octave on the sound spectrum; however, the “power behind frequencies decreases with each octave.”

Brown noise sounds help drown out background noise and may sound low and rumbling like a thunderstorm, waves crashing on a shore, an airplane engine or wind.

Pink noise, explained Today, “has a decreasing high frequency and sounds like gentle rain or a waterfall.”

While pink noise isn’t as low as white noise or as deep as brown noise, it’s still great for helping someone fall and stay asleep. This type of noise settles in the middle with “softer, quieter, and more flat” tones.

According to sleep experts, this TikTok trend might be on to something as pink and brown noise can be helpful depending on the person and the type of sleep help needed. A study by Dr. Phyllis Zee, professor of neurology at Northwestern University Feinberg School of Medicine, found pink noise improves sleep quality and memory.

“The effect here, at least for memory, is quite related to the ability of the sound stimulus to enhance slow-wave sleep,” Zee told TIME. “That’s very much tied to what part of the slow wave the stimulus is hitting on.”

Siest Sleep explained that brown noise can “clear your mind of chatter and calm your mind before sleep. Also, it helps mask other sounds so your brain is not interrupted when you sleep.”