Nothing. It's nothing. I feel nothing, I am nothing. Do I exist? Is this hand mine? This body? I could throw this hand into that wall and not feel a thing, even though people say it's mine. It's not, it can't be. It doesn't feel like mine.

Suddenly it's terrifying. It's like I'm being smothered but not having anything to hold onto either. Drowning on too much oxygen. You know the sensation in the back of your throat when you run for too long? When it's freezing cold? It's like that sensation is surrounding you. You don't feel it, but you are aware of it. It's horrible, it's scary, it's strange and impossible.

At the same time, there is too much air. The ground is miles below - I am drifting, helplessly floating through this great expanse of nothingness. Everything around me looks insubstantial. I put out a hand to a bookshelf, feeling its edges with my fingers. 3D. It's 3D.

I know that this is normal, but now, in this state of non-existence, it is baffling. I check my memory: has the world always been like this? I feel like everything I've known prior to this moment has been in 2D: anything else is inconceivable.

I have been thrust into a world that is at once familiar and completely alien. My mind struggles to make sense of it all yet my body knows what to do. It opens doors and presses switches even as my mind boggles. It's like a character in a game: someone else is controlling every movement I make, movements I am incapable of doing if I think for even an instant of them.

The lack of control is terrifying. My brain is swirling, the world is nonsensical and I am drifting in bewilderment through it all. Nothing is right: not my head, not this room, not anything. Everything that enters my head feels wrong and impossible. Words themselves are the worst of it - how do we do words? They require no thought, no conscious effort, but instead simply emerge. Does that mean they're not ours? Is someone else orchestrating our words? Oh god, I don't even control my words. Where do they come from? Who do they come from?

No-one else realises just how wrong the world is. I have been thrust into a tank, screaming and yelling for someone to help me, to make everything right but no-one gets it; no-one else can see what is perfectly obvious to me, that we are all being controlled by something other than ourselves. I pound on the glass but they cannot help: they do not realise how petrifying it is to be thrown into a world that makes no sense. They think I'm joking when I tell them that I don't exist, none of them quite realising just how fragile everything is.

I have to escape. I'm on autopilot, my mind far away as my body does what it must. Somewhere the hands - my hands, I remind myself - are fumbling for something. I look at what they hold - a shiny, rectangular piece of metal: flimsy but with sharp edges. Razor sharp.

It's dances over my skin (only it's not my skin - but it is) and somewhere in the back of my consciousness I know that this is going to hurt. And yet I don't really believe it. I can't believe it. It can't hurt - nothing can. I don't exist. I don't have feelings. So I press down and -

The pain hits me like a tidal wave of icy water. It crashes over me, thrusting itself into every corner of my body, filling each cell with life. Suddenly I'm gasping, surfacing from the suffocating non-existence and emerging, spluttering into the world.

But it's wonderful. I'm me again. I feel, I am. I exist and it's amazing. The blood is proof. I can feel and I can hurt. There is blood beneath this skin of mine and I can feel it as it trickles from the mark and slips down my arm. The world is here: immediate, tangible.

Slowly, I reach out a hand to touch the door handle. It's 3D and that it makes sense. This is the way the world is meant to be. My feet are on the floor, the horrible drifting sensation is gone.

I lean back against the wall, sighing with relief. My head is mine again. I can relax.

A.N. I apologise if this was jumbled or made no sense. It's as accurate an account as I could write of a feeling that I get occasionally, but because it's such a scary and confusing feeling articulating it at all - let alone coherently - is almost impossibly difficult.

Obviously I don't condone any sort of self-injurious behaviour.