You know those awful nights when all you can do is lie in bed and stare at the ceiling, fixating on some stupid social faux pas? The ones where it’s almost 3 a.m., and you start wondering whether it’s possible to overdose on melatonin? Typically, you’ll grab your phone and type in something like “how to fall asleep fast,” only to end up with frustratingly vague suggestions like “just relax.” But if you keep on scrolling, you may also stumble upon the curiously named “brown noise,” alongside rave reviews from insomniacs across the country. And before you ask, no, it’s not the same thing as the “brown note” that South Park made famous—meaning there’s zero risk of soiling the bed.

Rather, brown noise (also known as “red noise”) is an ambient “color” of noise that sits on the lower end of the sonic frequency spectrum. Unlike its better-known cousin white noise, brown isn’t every audible frequency combined into the sound of television static. It sounds more condensed, powerful and deep, with a slight rumble that brings to mind a rolling thunderstorm or a rotating tumble dryer, which light sleeper Abigail Castel called extremely “soothing” as someone who “can’t sleep well in silence.” In fact, she even prefers it to “pink noise”—another frequency typically associated with gentler environmental sounds like calm seas or rustling leaves—even though it’s been shown to decrease the time it takes to fall asleep and help people remain in the restorative deep sleep phase.

“[To me, brown] is the softest of them all,” she said, explaining she spent several months working her way through different slight variations of white and pink noise. “It most resembles the sounds of a storm, or driving on an open highway in the rain,” she listed. “It’s truly like listening to what a rainy Sunday nap in October feels like.”

Despite recent U.S. search data showing that white noise remains the most popular way to block out external sounds, Google Trends curator Katie Seaton pointed out that searches have leveled off. Interest in color noise, on the other hand, more than quadrupled over the last 18 months, and this surge appears to have been partially propelled by searches for brown noise almost doubling this past year.

This shift doesn’t come as a surprise to noise connoisseurs like Castel, who explained that pink noise now feels “too harsh” and white noise is “actually unbearable.” This was echoed by a fellow brown noise lover Rivka Rose.

“I find white noise to be a bit abrasive,” she said, adding that the sound “actually makes [her] feel more anxious than relaxed.” So in lieu of a traditional white noise machine, Rose has begun to use a fan and recorded deep brown noise in order to get some shut eye—and block out the sound of her partner’s snoring.

For others, brown noise can act as a form of sound therapy that helps to offset various mental and physical health issues that prevent them from a good night’s rest. Brian Ziff, a photographer, says he used a white noise machine for years due to a combination of OCD, insomnia, intrusive thoughts, and sensitivity to sound. Even so, he still wanted to alter the sound by “reducing the highs and exaggerating the bass frequencies,” which he explained was actually just an attempt to “emulate brown noise.”

“White noise and pink noise are marginally helpful, but I’m always aware that they’re present,” Ziff said. “Brown noise creates a harmonious balance between my thoughts and all external stimuli.”

Brown noise also holds promise for people with tinnitus, a condition that manifests as a chronic ringing in the ears. According to clinical audiologist Dr. Amy Sarow, some of her patients “prefer the deeper quality of brown noise over white noise or other colors of noise,” as those “with high-pitched tinnitus find that the sharpness of white noise is too harsh and prefer the smoother, rounder sound of brown noise.”

One person who agreed with Dr. Sarow’s observation was musician James Rowland, who’s spent the past 15 years experimenting with different kinds of sounds to treat his tinnitus and insomnia, only to find that “sleeping with background noise because it helps me to switch off.”

“It’s like the only time I’m experiencing true silence,” he said, though he noted that “bad sounds can be very upsetting and anxiety-inducing.” As a result, brown noise has become one of his staples, as it’s more effective when it comes to neutralizing the ringing in his ears.

“It’s phones and laptops that have speakers with no low end, so pink is just all fizz,” he said. “Brown sounds better on cheap speakers, because it’s louder on the lower frequencies. It gives them an extra push out a phone or laptop, and that is going to do better at covering sounds in the room.”

Sarow pointed out that brown’s lower frequency has been shown to improve executive functioning and result in improved performance on test of memory when compared to quiet. “The result can be an effect of neurons firing in the hypothalamus to promote quicker access to information flowing from the hypothalamus to the cerebral cortex,” she said, mentioning that there’s also been talk about “brown noise helping those with ADHD.”

That said, there’s still a lot to learn about how brown noise works and whether it truly is the superior color noise for sleep. But with its growing popularity, there’s a strong likelihood that we’ll be getting more conclusive studies in the near future, particularly if there are other positive neurological effects. For now though, we’ll say that while there may be several different reasons for the noise’s popularity, if you're having trouble sleeping, it couldn’t hurt to try the sound of brown.

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