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Since the term ASMR was coined in 2010, millions of YouTube videos from around the world have gotten in on the fun. In a video, you'll typically see an "ASMRtist" deliberately stimulate a sensitive microphone with a number of normally subtle or inaudible sounds: very soft whispering, lip sounds (like smacking and eating), clicking, tapping, hand and hair movements, and brush strokes from makeup, painting, and drawing tools. The community refers to these sights and sounds as triggers, and they elicit a pleasurable tingling sensation to those who are susceptible.

You know how you feel when you hear nails on a chalkboard? ASMR is basically the opposite of that. It's a physical sensation that enthusiasts call a "brain massage" or, more commonly, "head tingles." It feels like a pleasurable tingling that usually starts in your head and can travel down your spine. A 2015 study of 475 ASMR community members showed that 98 percent used ASMR for relaxation, 82 percent for sleep assistance, and 70 percent for stress relief. As one ASMRtist told CNBC, "It's a very pleasant, natural high state that you want more and more of."

It's worth noting that ASMR is different than frisson, which is when you get chills or goosebumps from an intensely emotional experience, such as while listening to music. Some scientists believe that sensation is tied to unexpected moments in music, which triggers a flood of the pleasurable hormone dopamine. This can be accompanied by an elevated heart rate, which is the opposite effect of ASMR.

In order to understand more about ASMR, researchers from the University of Sheffield put it to the test. For a study published last month in PLOS ONE, they measured the experiences of people who did and didn't experience ASMR, first in an online survey that had them watch YouTube videos, then in a real-world lab experiment. In the survey, participants who identified as having ASMR reported "more frequent tingling, increased levels of excitement and calmness, and decreased levels of stress and sadness" while watching ASMR videos, as compared to people who didn't experience ASMR.

The lab experiment again exposed both groups to ASMR-triggering videos, this time while the researchers kept tabs on their heart rate and skin conductance (a measure of emotional arousal). The ASMR participants showed a greater drop in heart rate and a higher increase in skin conductance than non-ASMR participants when watching the videos. They also experienced "significant increases in positive emotions including relaxation and feelings of social connection," according to the authors.

"Our studies show that ASMR videos do indeed have the relaxing effect anecdotally reported by experiencers — but only in people who experience the feeling," Dr. Giulia Poerio, the lead author of the study, said in a statement. "This was reflected in ASMR participants' self-reported feelings and objective reductions in their heart rates compared to non-ASMR participants."

So how does ASMR stack up to other activities? Poerio said that those reductions in heart rate were comparable to the stress-reducing effects of things like listening to music and meditating. Prior to this study, Shenandoah University Professor Craig Richard told Scientific American that ASMR "could someday be approved as a medical treatment to help people with insomnia, anxiety, depression, and/or chronic pain — but there is still a lot of research and clinical testing that needs to be done." This study might be a step towards that goal.

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Learn more about how YouTube videos about ASMR and other niche topics are spreading like wildfire in "Videocracy: How YouTube Is Changing the World...with Double Rainbows, Singing Foxes, and Other Trends We Can't Stop Watching" by Kevin Allocca. The audiobook is free with an Audible trial. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.