Lately, when I go back to sleep after waking up, I have terrifying lucid dreams.

They’re vivid and I feel like I’m stuck and won’t ever escape. A few times, I’ve convinced myself I’m actually dead and will be trapped in a dream for eternity. I wake up covered in sweat, wanting to never go to sleep again.

But yesterday morning was different.

My alarm went off and, as usual, I reset it to give myself an extra 15 minutes sleep. What followed was my familiar experience of being trapped and desperately wanting to wake up. But then I did.

I was laying on my side in bed, so tired I could hardly keep my eyes open, when I heard someone open my front door. I knew I was home alone, so I had no idea who it could be. I was so exhausted I couldn’t move, and then I saw a man walk into my bedroom. He walked straight past my line of sight, until he was out of view. I expected to be attacked. This man was surely going to hurt me, and no matter how hard I tried, I couldn’t move.

I’m not sure how much time passed before I actually woke up. I looked to my right expecting someone to be there. But no one was.

What I had experienced was sleep paralysis – a feeling of being conscious without being able to speak or move. Historically, it’s been described as sensing an ‘evil’ presence, and many people report seeing demons or an intruder.

Dr Michael Breus, a clinical psychologist and expert in sleep medicine, told BuzzFeed, "most patients say... it feels like you woke up dead".

"You know that your mind is awake and your body is not — so you're trapped, essentially."

When we sleep, we alternate between REM sleep and NREM (non-REM) sleep. During REM sleep, our body goes into a state of atonia - essentially paralysing the muscles. Our body does this so we won't physically act out our dreams, which we are quite literally 'seeing' via our visual cortex. During sleep paralysis, our brain awakens while our body remains paralysed. We're still transitioning from deep REM sleep, and therefore can experience a certain type of hallucination.

For some people, sleep paralysis is accompanied by a sensation of intense chest pressure, such that they wake up gasping for breath. An episode can last anywhere from 20 seconds to a few minutes.

While my experience haunted me all day, I found some comfort in learning about the ubiquity of sleep paralysis. People have been trying to make sense of it for centuries, describing a certain set of symptoms, and a feeling of terror. That's probably what Swiss artist Henry Fuseli was trying to convey in his painting, The Nightmare. 

Research suggests sleep paralysis might be triggered by irregular sleep habits or sleep deprivation - both of which would explain mine.

It's widely accepted, however, that sleep paralysis isn't dangerous. I Googled it. Extensively.

"It does not cause physical harm to the body and there are no clinical deaths known to date," says Dr Breus. "The biggest thing is to educate people to not be afraid. In all likelihood, they just need more rest."

LISTEN: Much-needed advice for sleep-deprived mums. (Post continues...)

After my distressing dreams, and recent terrifying experience, I have a newfound empathy for those who suffer from chronic sleep problems - like night terrors, or sleepwalking. For many of us, going to bed is a source of comfort and relief. But for some, it's riddled with anxiety. What their mind and body will do when they're not conscious is unknown.

I can't imagine how exhausting that battle would be.