"It feels like you've woken up dead." What makes sleep paralysis so terrifying.

I can feel it before I can see it.

I’m awake. I’m sure of it. I try to move, to run out of my bedroom, but I’m stuck. It’s as though something is sitting on my chest and I can’t breathe.

There’s a dark figure. Is it an intruder? All I know is that someone bad is trying to hurt me and there is nothing I can do about it.

I’ve never been so terrified and I think for a moment that my heart might just stop beating.

After what feels like a number of minutes, I realise I am dreaming – even though I’m in my bed, with my bedside table and my wardrobe slightly open. But I’m trapped.

I’m stuck inside a dream and I’m yelling as hard as I can but no one can hear me. It’s like Locked-in syndrome, or being injected with a paralysing drug that means your brain is conscious, but your body is useless.

As the ‘thing’ descends upon my body, and I think it might suck the life out of me, I wake up.

And for a moment I wonder how I will ever let myself fall asleep again.

LISTEN: Debbie Malone is a psychic investigator. Post continues below. 

***************

As we fall into rapid eye movement (REM) sleep, our brain releases chemicals that function to paralyse our muscles, preventing us from acting out our dreams.

But the sensation of coming into consciousness, while the body is still paralysed, is deeply distressing.

Suddenly, it can feel as though you’re awake in a nightmare, or, as clinical psychologist Michael Breus says, “it feels like you woke up dead… you’re trapped”.

And there’s a term for it: Sleep paralysis.

Accounts of sleep paralysis are as old as sleep itself.

Demons. Intruders. Evil spirits. Alien abductions. These are the most common characters that appear in the waking nightmare.

The phenomenon is referenced in the Chinese book of dreaming dating back to 400 BC, and 10th century Persian medical texts. It has always had supernatural connotations, often explained as an evil entity visiting someone in their sleep.

In Salem, Massachusetts, during the witch trials, many envisaged female demons descending upon them, and such experiences were used as evidence that witches were among them.

The first clinical observation of sleep paralysis came from a Dutch physician in 1664 who studied a 50-year-old woman with ‘Night-mare’. The word ‘mare’ literally translates from Old English to mean evil spirit or goblin that rides on people’s chests as they sleep.

In present popular culture, sleep paralysis has become the stuff of horror.

Perhaps it is within this state that many of us claim to have seen ghosts or spirits, seemingly straddling the worlds of the living and the dead.

But scientists say the phenomenon is a neurologically driven process; a glitch in the human sleep cycle.

Up to 40 per cent of us will encounter sleep paralysis in our lives, with a minuscule portion of the population experiencing recurrent sleep paralysis. Experts say it can be the result of extreme fatigue, Post Traumatic Stress Disorder (PTSD) or other mental disorders.

It is rarely an indication of a more sinister condition.

But when it happens, it brings with it a sense of sheer, undiluted, visceral terror, unlike any nightmare you've ever had.

And perhaps that's why, since the beginning of time, humans have found so many different ways to come to terms with it.