Readers may have gathered that I am troubled by frequent, sustained migraines - these are always on the Left side; and indeed one-sided, severe headaches of a stereotypical pattern is pretty much the definition of a migraine.
Having migraines has been very limiting for me over the past twenty-something years - I have missed all sorts of good things, and my travelling and exploring has been cut down considerably (plus, they hurt! and the treatment isn't very nice either).
But one compensation has been that when the migraine pain has been treated, I am at the maximum of creativity of which I am capable. In the sense that I am more likely than at other times to make a breakthrough in whatever it is that I am working on. Indeed, when I have gone for an occasional couple of weeks without a migraine then I have noticed myself getting less creative.
Why might this be? I had usually supposed that the slight delirium of the treated-migraine state might be responsible for a more associative, looser, semi-psychotic way of thinking; but I recently had the notion that it might be a Right-brain- Left-brain balance sort of thing.
An early symptom of the developing migraine is nominal aphasia - an inability to find word names - indeed, this is so characteristic that my wife has sometimes noticed and told me I was getting a migraine when I hadn't myself noticed. Together with the fact that the pain is on the Left side, this may suggest that the migraine pathology (whatever it is) is located in the language area of the Left cerebral hemisphere (soewhere like Broca's area, perhaps).
And this might perhaps mean that during a migraine the Left side of my brain is impaired and therefore the Right side more dominant - and it seems true that during the migraine my thought is more 'holistic' (and creative, as I said) and certainly it is less precisely-detailed, consistent with Right-sided dominance.
If this rather vague hypothesis is correct, the there should be a pattern of more-creative-less precise thinking during Left-sided migraines; and more-precise and less-creative thinking among Right-sided migraineurs - although quite likely this only applies to migraines affecting certain parts of the cerebral hemispheres.
In passing; my migraines are boringly simple in form - merely a pain and referred skin tenderness starting in a particular place of my neck, getting more severe and moving to behind my eye. I don't get any exciting visual 'aura' as a warning: no flashing lights, zig-zags, bling spots (although most of my close family do or did - we all suffer migraines to some degree).
But, interestingly, the only reliable prodrome, that sometimes happens and will predict a migraine a few hours ahead, is the idea spontaneously coming-into my head that I don't feel at all migraneous, and maybe I have gotten over migraine and won't have any more of them...
NOTE ADDED: Today was a pretty good example of migraine-enhanced creativity. I was woken early with a particularly nasty migraine that went on for about 8 hours despite escalating treatment - then felt rather wretched from the treatment and the after effect --- but my mind was bubbling with ideas and I ended up scribbling pages of notes and writing five blog posts (including one at Jr Ganymede), so far... (This being a weekday when I have no face-to-face teaching - and which I try to keep clear for thinking, scholarship and 'research' of a theory-focused kind.)