Most of us will be put under general anaesthetic at some point in our lives so that doctors can operate on us without us feeling anything, but how exactly does it keep us unconscious through serious pain? Well, to be honest, scientists aren't totally sure how it works, as this episode of SciShow explains. But they do know what happens to our brains when they're dose-up on anaesthetic, and the results are pretty cool.

To start with, there are generally two drugs involved in putting you under general anaesthetic – the first knocks you out fast, and the second one keeps you that way throughout the surgery.

The dose of this second drug is the one that anaesthetists tinker with in order to make sure we don't wake up too soon, or go to deep under. The ideal amount is just enough to make sure we wake up with no recollection of what's just been done to our bodies.

But even though being put under anaesthetic often feels like falling into a deep, dreamless sleep, brain scans have shown that the process is actually nothing like sleep. Not only are different areas of the brain activated, they also don't communicate with each other under anaesthetic as they normally would while you're asleep.

What's more, there's no rapid eye movement under anaesthetic, and the brainwaves look a lot like the brainwaves of coma patients, as Hank Green explains in the video.

Even more interesting is the fact that there are four different chemicals that work as anaesthetics, and they all have the exact same effect on the human brain. Scientists are now beginning to narrow down the pathways they operate on.

So then how does anaesthetic work? Well we'll let you watch the episode above to find out, but let's just say that our brains are fascinating, and so are redheads. And next time you go in for surgery, don't forget to thank your anaesthetist.