If I am not woken suddenly—by an alarm clock, for example—I often find myself in a state on the cusp between sleep and wakefulness; in reverie. And often in that oftenness some questions that have been in the back of my mind will find their way to the front. The other morning—the one that triggered this post—I "woke", and started thinking about the West Antarctic ice shelf, as one does.

In this state, I am aware at some level just below the surface, that I am awake. That awareness is deceptive, as becomes obvious when the phase change to wakefulness actually does occur, with its accompanying I'm awake now. When that happened, I was still thinking about ice, but the context of the activity had changed. The most obvious change was my sudden alertness to my surroundings. I had moved out of that inner world to which the world that contained me—the bedroom, the house, the noise of trees and birds and traffic—was connected by only the subconscious trip-wires that will be snagged by, say, the smell of smoke; and into the state of thinking wakefulness where, while the pattern of thought may be the same, the mental terrain has become spare and hard-edged, analogously to a transition between watching a movie and reading text, even if a movie that I am present in, a book that I am writing.

Where I had been following a seam of argument through a dream-rich montage of images from the ice down into the Southern Ocean to the ice-scarred bottom, I now found myself working it in the dimly lit bedroom, with the morning light seeping in at the edge of the vertical blinds. I'm awake now.

My waking mind would maintain that the drowsing mind would generate conclusions less reliable, more appropriate to a dream, but I have too many times woken with a new approach to a thorny technical problem, to accept that self-serving hypothesis from the well-lit side. The contrast with the spare environment of my waking thought brought home to me the paucity of visual imagination that I have taken for granted, relegating the imagery of dreams to a completely separate realm.

Yet they are not as separate as I had imagined, as the experiences just mentioned ought to have led me to suspect. Such enlightenments had, however, happened in the dark, simply presenting themselves to the waking consciousness. In this instance of the emergence of wakefulness I had the chance to see a process of thinking happening within the the context of dreams, with all of the imaginative richness that implies.

I don't conclude from this that I might be able to draw the imaginative content of dreaming into the conscious process of following the quirky trails of ideas. That gate closes with I'm awake, but it gives a tantalising glimpse of the mind's sleeping mode, complementing the now far too infrequently remembered fragments of my dreams.