The essay does not consist of the phrase "I am a fish" 400 times, either. I have some originality, you know.

It is currently 10 to 1 in the morning, and I am buzzing on caffeine. 100mg of the stuff, to be precise, delivered in two tiny ProPlus tablets just over an hour ago. I don't drink coffee, you see, or very much in the way of Coke or Red Bull, so I am very sensitive to this particular drug. Add in the fact that said tablets dump the caffeine into your system very fast, and it seems unlikely that I'll get any sleep for another hour or so at least.

It probably won't surprise you to learn that I'm not really much of a pill popper. If a doctor tells me to take something, I will, and if I have a really bad headache or pain that's stopping me from sleeping, I'll take a couple of paracetamol, but that's about it. The longest course of medication I've ever taken was for six months, I think, when I was taking antimalarial pills once a week, but I usually find that sleeping for a long time cures most things eventually without the need for chemical involvement.

So why is it that my brain is being the neural equivalent of a frisky puppy right now? It's because I have work to do. Specifically, the last tutorial essay that I have to write in Oxford. And given that I'm kind of tight for time right now, and that I only wrote my previous essay yesterday morning, I'm more than a little bit tired, so if I wanted to get this work done in time for the 10am tutorial tomorrow, artificial stimulation was really the only way to go. I've done this a total of twice before, once using "Kick", the horrible cheap Tesco equivalent of Red Bull, and once using ProPlus. When I say "Kick" is horrible, I'm not kidding. It tastes vile, as though the lovechild of a strawberry and a mango died a terrifying death in a bath of acid before having a truckload of sugar poured over its still-twitching body. But it does contain 300mg of caffeine and cost about £1 per litre, and this was all that I needed in order to write an entire essay in four hours after a long day. It was also just shy of the amount of caffeine required to experience caffeine intoxication, a condition in which you apparently get twitchy and paranoid. This sounds vaguely exciting for some reason, but I have yet to see what it's like.

This time around, I knew what I needed to do, and it worked. The tablets went down at about twenty minutes to midnight, and roughly an hour later I had added an entire typed page of very detailed notes to the essay plan, ready to be edited into a coherent whole. Well..."coherent" is probably pushing it, but it did at least come to a conclusion. The frantic speed at which I was typing had also slowed down, an indication that the peak of the caffeine high had worn off. A few more minutes to let it subside even further, and I should have the right balance of alertness and common sense to massage these notes into something resembling a logical argument.

Despite the fact that I'm comfortable with using a chemical method like this in order to boost my productivity, I find it incredibly odd how easy it is to entirely change my behaviour with two small pills. An hour and a half ago, I was slumping forward at my desk, unable to see which way the essay was going to go - now, it's about 20 minutes of editing away from being finished. Even though the physiology of my body has barely changed (I have been awake for just as long, and all of the physical effects of that, and of the stress I've been under these past few days, are still present), the subjective experience has changed completely. Nor is it some kind of illusion - the alertness I gained really did allow me to see what I should be writing about next. It does make you wonder how much of the everyday experience that we have is due to the world around us, and how much is due to hormones, to the chemicals sloshing around through our bodies' various systems, and to the substances that we poke into our faces.

More than that, though, if simple things like my productivity can be altered through such straightforward means, where is the dividing line? What else could I change? Cases like that of Phineas Gage come to mind (WARNING: Fairly gruesome medical illustrations), where high-level things like personalities entirely change after one's brain is selectively damaged. This then starts to raise philosophical questions, such as "Where is the part of me that I call 'me' actually located?" Given that the essay I've been writing is about consciousness in the first place, this kind of thing has been running around my mind for a while.

Because I'm not an idiot, I have no wish to try some of the more exotic substances around, that can bend one's apparent reality in unpredictable ways. I think that I do now understand more why it is that other people experiment in this way, though. If the effects of such substances were predictable, what else could you do? What else could you create? And would the results be an experience that was in any way less "authentic" than that which you see every day?