As if to punish me for mocking her creation yesterday, last night Neuralgia the Goddess of Headaches caused me to wake after only three hours sleep with a splitting headache. It was so bad I had to get up and take a couple of painkillers rather than just lie there and hope it would go away again.

Well I'm sorry, but that actually proves my point. In pre-painkiller days all one could have done about such pain would be to have gone back to bed and hope to sleep it off. Well, duh. Nocturnal headaches, especially ones that wake you up, are even more pointless that the regular variety. Where is the evolutionary advantage in them?

Still at least being awake at such an unusual hour - that is awake after approximately two to three hours sleep rather than at around two am - did give me the opportunity to observe the dream engine running at capacity whilst awake. In particular I was impressed by what was going on in my visual cortex. Every time I closed my eyes I was assaulted by a intricate brightly coloured symmetrical moving pattern of ever increasing complexity.

I am curious as to what this actually was. The visual cortex going through a self-diagnostic test? Or was it just that I'd interrupted a dream by waking up when the dream software was still running at full capacity, necessitating a few minutes for it to shut down?

And it was only a few minutes. By the time I'd got back into bed again after pill-popping, it had gone, replaced by the standard murky slow moving shapes I always see when closing my eyes at night. With the occasional fluorescent pineapple ring floating past.

I am inclined to think of it as some kind of diagnostic mode for the visual cortex as these a patterns are similar to those seen when under the influence of a psychedelic. Apparently. Perhaps hallucinations are caused by this mechanism being accidentally tripped?

Whatever the mechanism of dreams though, I still wonder where some of the memories in them come from. What a memory actually consists of is still poorly understood even now, but one would hope that it's something reasonably permanent. What puzzles me therefore is when, in a dream, one "remembers" something which quite patently isn't true in the real world and which one has never dreamed before. For example, the kind of thing I'm talking about is when one "remembers" that "...of course there's always been an underground tunnel linking Brighton and London which only takes ten minutes to traverse".

I wonder if these false memories are actually constructed on the spot by the dreaming brain or whether all that is happening is the experience of remembering being faked? Whichever one it is, imagine the implications for the entertainment industry when this can be harnessed for total immersive interactive movies...

One memory that's always popping up in dreams is how to fly. Now I wonder where that comes from?