If you are yet to stumble across one of these videos that are spreading like wildfire over the net, you might be wondering what in the world is going on. ASMR stands for autonomous sensory meridian response, which is the term used to describe the sensation people get when they watch stimulating videos that usually involve some kind of personal attention, like a slow almost sexual voice whispering intricate descriptions into your ear.

This ASMR phenomenon was started by Jennifer Allen in 2010, when she created a Facebook group dedicated to finding out whether there were any other people that experienced the pleasurable sensations she had started to feel while watching certain videos. For her, it started with videos of space, where she claimed to feel a tingling wave-like feeling that spread through her scalp and down her spine.

How ASMR triggers these feelings differs from person to person, and some people will feel nothing at all. There is no scientific evidence that the sensations are brought on by these videos either, so it is all based on anecdotal information from around the internet. Like synesthesia, which is a neurological condition that when given information of any kind stimulates several of your senses instead of one, it was first discovered by way of individual reports. Unlike synesthesia however, it has not depended on brain imaging for cultural acceptance.

With ASMR, some triggers include whispering voices that are recorded and spoken up close through the listeners earphones and that pay particular attention to the listener, such as quietly blowing air into each ear (or rather, giving the sensation of this through a microphone).

Some people on the other hand enjoy listening to the sound of tapping on wood or metal, stirring a bowl of soup, the crinkle of paper or plastic or even trickling water. Others are triggered to experience ASMR by more of a role play, where the voice in their ear pretends to be a hairdresser, recording scissors and hair combing for the listener and talking them through the process. Even going to the doctors can be a fetish for some. However, this pleasurable tactic is actually not intended to be sexual exactly, but the tingling sensation that it evokes is supposed to be soothing, and because of the nature of the videos—listeners are drawn to what they like, which is similar to sexual pleasure and arousal.

Another aspect of ASMR that is similar to sex, is that people appear to grow tolerant of triggers if they listen to or watch them too much. Maria, who runs the Gentle Whispering channel (which has more than 1.9 million subscribers on YouTube) spoke to Vox and told them how important it was for ASMR video makers to keep things fresh.

Similar to a meditation app that tells sleep stories, ASMR is frequently used to help a listener fall asleep, as it apparently triggers prime relaxation. Maria describes that when she first discovered this sensation as a child in kindergarten, as her friends would run their fingers over her forearms, she told Vox that it put her in a trance-like state. She said that “It wasn’t the sensation of them touching my skin as much as the attention they were giving me.”

Gibi, another ASMR whisperer, published a globally trending video in 2018 called The ASMR Sleep Clinic | Tingle Experiment and told The New York Times that “If you fall asleep during my video, that’s a compliment,” and that her sleeping fans tend to leave videos running. Her main goal is to give her fans a massage for the mind, and relax people. The actress Eva Longoria also gave sleep ASMR a shot with her YouTube video for W magazine.

There are literally thousands of ASMR videos on the internet today, and they vary drastically in content. There has also been an influx in visual ASMR videos, such as the squeezing of sponges or mixing of paint.

Craig Richard, a professor and researcher at the Shenandoah University School of Pharmacy in Winchester and founder of a blog called ASMR University, told The Washington Post that it is okay to be sceptical. “If you don’t experience it, and there’s no published research, I think it’s appropriate to be skeptical. I don’t know if I would believe it if I didn’t experience it myself.”

Whether you’ve grown a tendency to watch slime videos before falling asleep or you simply can’t avoid them on your Instagram feed, one thing is certain, ASMR is here to stay. As more research is being done, they may adapt into videos we wouldn’t know were ASMR based in the first place.