The video consists of nothing but 13 minutes of a woman lightly tapping and scratching various books. So, pretty mundane, right?

Here's the kicker: It has over 200 000 views on YouTube.

It's been dubbed a "brain massage", "head tingle" and even a "head orgasm", but the more scientific term is autonomous sensory meridian response, or ASMR.

The phenomenon, characterised by a pleasurable tingling that begins in the head and moves down the spine to the limbs, is felt by loads of people, it turns out.

There are two types of episodes according to the ASMR Research group.

The first kind, namely type A, is spurred on by internal triggers, such as your internal thought process.

Then there's type B, the one that has scores of people entranced...

Type B episodes are characterised by external triggers - and there are loads of them.

Common triggers for the phenomenon include watching someone complete a simple task (cooking, typing, writing etc), viewing instructional videos, close attention from another person and slow, accented or unique speech.

But there are a variety of other triggers as well, such as lip smacking, white noise, whispers and painting. Even brushing and clicking sounds are popular triggers.

ASMR has experienced greater exposure thanks to the internet - social news site Reddit boasts an ASMR sub-reddit (sub-section) with over 22 000 readers viewing and posting ASMR clips.

The clips posted to Reddit even include tags to give more information about the video. So you'll see tags like "intentional" and "unintentional", denoting whether or not the video was made to purposefully trigger the effect.

The ASMR phenomenon has also spawned numerous role-playing clips, featuring women (and sometimes, men) acting as anything from optometrists to hair stylists. In fact, there are even channels devoted solely to whispering (yes... whispering...).

However, the phenomenon isn't for everyone though, so if you've never experienced it in some form, you're unlikely to. But it has to be said, I found myself falling asleep to these videos quite often.

Page two: Some popular ASMR videos