It might seem odd to think of dreaming as a type of consciousness: but as far as the brain is concerned, dreaming has much more in common with being awake than with dreamless sleep. For example, large protein molecules, so important for everyday brain function, appear to be stock-piled whilst we sleep, or at least while our brains are in dreamless sleep. Experiments show that during the critical stage of sleep which is associated with dreaming, when that the eyes flick rapidly back and forth (rapid eye movement or REM sleep), protein manufacture plummets to that of normal consciousness.
By the same token, brain waves recorded from electrodes on the surface of the scalp during dreamless sleep, take the form of smooth waves of electrical signals undulating, as masses of brain cells all work together in harmonious unison. But during wakefulness and REM sleep, a completely different picture emerges: each brain cell does its own thing. This neuronal assertiveness gives rise to a desynchronized record of "fast" waves on the electroencephalogram (EEG) record, which is virtually indistinguishable between waking and dreaming states.
As far as the brain is concerned, then, dreaming is effectively wakefulness: but as we all know a dream offers a very different type of consciousness to the pleasing and reassuring continuity of a waking experience. In dreams, adult logic no longer applies. And a dream is very rarely of a specific event that can be identified within a particular time and space frame of reference. Instead of elaborate, abstracted thoughts, dreaming amounts to a far more literal consciousness, one reactive to the immediate here and now, where we are no longer fully in control. How similar to a small child's outlook where one is much more the victim of the moment, a passive recipient of bombardment by the senses. In dreaming, and arguably in childhood, one lurches from the pull of one isolated and urgent event to the next. So, perhaps dreaming could be viewed in some way as recapitulating the consciousness of childhood - it is a type of consciousness that could be characterised as more flimsy, less robust than in our adult day-time lives.
A few months ago, I suggested in these pages that fetal consciousness might be best understood using the model of a "dimmer switch", where consciousness grows in degree as the brain grows. The ruptures in continuity, and focus on the here-and-now that can characterise dreams, might then be viewed as hallmarks of a smaller degree of consciousness, a consciousness comparable to that of children, where the brain is served with far fewer connections between neurons. Consistent with these parallels is the observation that the younger the brain, the more time spent in REM steep.
If you go along with the similarities between childhood and dreams, then the dimmer-switch model of consciousness makes perfect sense. Perhaps at night, our diurnal brain chemistry conspires with the under-stimulation of the senses to simulate in the brain temporary conditions similar to those resulting from the sparse connections of childhood: in both cases a smaller degree of consciousness would ensue. Experiencing a nightmare, and indeed the terror that seeps into the first few moments of waking from it, might merely indicate a more modest degree of consciousness, a consciousness where one's personalised neuronal connectivity forged through life's experiences, is sporadically out of commission.
! Susan Greenfield is a neuroscientist at the University of Oxford, and Gresham Professor of Physic, LondonReuse content