Cures for sleeplessness, as even part-time insomniacs learn, suffer from the law of diminishing returns: familiarity breeds wakefulness. Another problem is that, while boring strategies won't hold the attention until sleep comes, really interesting ones may cause an abrupt jolt into wide-awake alertness. I could never do with counting sheep: their sameyness, which is presumably their whole point, makes the whole exercise unmanageable as well as dull. The most reliable method I know, though you may have to be halfway towards sleep for it to work, is to set off down an unfamiliar country lane and see where it leads. I've discovered some richly detailed hills and woods and villages, none of them identifiable in the waking world, on these pedestrian journeys to what's aptly called the Land of Nod. What fascinates and slightly troubles me is the fineness of the detail: I'll find myself closely observing a curious plant (perhaps something half-familiar, but seldom so big or so small or quite that colour) or an insect on an ancient wall with all the intricacies of cobwebs and dust, crumbly brick and loose mortar. Over the years, some of these imagined places have even organised themselves into a geography of their own: so, just before turning a corner, I suddenly know what's going to be on the other side and then recognise a previous dreamscape, as slumber takes over.

But there are times when the tired inner eye won't focus on anything so coherent: it's then that you have ...