Some Questions and Answers

What's Sleep For ?

Most sleep researchers are agreed that sleep provides recovery, but what exactly is recovered is another matter. Unfortunately, we haven't the technology harmlessly to get inside living cells of the sleeping animal, especially neurones or glial cells within the human cortex, where we know sleep is of particular importance. Besides, sleep must have several functions, evolved to suit the circumstances of various animals, and probably not the same for humans and mice, for example. For the mouse, sleep stops it running about aimlessly and conserves much energy by confining it to the insulation of its nest where it can huddle against other mice. It can't sit still and relax in wakefulness as this entails thinking, watching, reading etc - behaviours obviously beyond the repertoire of its simple cortex. We humans can easily do this, and so sleep is not necessary for our energy conservation. If, instead of sleeping over-night, we lie awake but relaxed, the extra energy needed is only the equivalent of eating an extra slice of bread - hardly worthwhile. On the other hand, our large and complex cortex requires sleep rather than relaxed wakefulness for its recovery, whereas the mouse's simpler cortex probably needs little sleep in this respect. Although a rat will die after about two weeks of total sleep loss, this is a remarkably long time in proportion to its life-span of two years. Its death through sleep loss has something to do with its failure to conserve body heat - but no body organ seems to fail, including its brain.

What Happens To Us When We Have No Sleep ?

For mammals with advanced brains, like humans, sleep is by the brain, for the brain. To be more specific, it's really for the cortex as most brain areas below the cortex, including the sleep control centres, don't sleep. Thus, the real effect of sleep deprivation is on our cortex, particularly the human frontal lobes, which comprise about 30% of the cortex. This latter region works the hardest during wakefulness and can't go "off-line" during wakefulness. It's the region that makes our behaviour "human" - so, with progressive sleep loss, not only do we become more sleepy, but our behaviour becomes more like that of a zombie or automaton. Spontaneity in behaviour declines, we become apathetic and don't know where to focus our attention. We become creatures of routine, can't deal with anything new, have dull and stilted speech, and become forgetful. Personality changes include irritability, being less able to suppress our more basic emotions and to "sense" the feelings of others - hence we become difficult for others to cope with. All these behaviours reflect frontal lobe failings. Although there are claims that our immune system is impaired by sleep loss and we may become mildly diabetic, this is probably wrong, as such effects are more likely due to other accompanying stresses. When we usually go without sleep, it is through overwork and other pressures, with sleep loss just being one of the consequences.

How Much do We Need ?

Zoo animals sleep more than in the wild, horses longer in stables than in fields, and the well fed cat more than the one that has to hunt for its supper. We also can sleep well beyond our usual levels if we stay in bed all day, but we don't need it - just like that extra helping of yummy dessert and all those cans of Coke. These are not for satiating hunger or thirst but for pleasure - and the same goes for some of sleep. So, how much of our usual sleep is really necessary ? After a night of no sleep, the next night we will regain less than half of that lost sleep, and feel fine. We regain all of the lost "deep" (stages 3 and 4) sleep, found in the first five hours of normal sleep, which I still call "core sleep" - it seems to be the sleep most beneficial to the slumbering cortex. Core sleep gradually gives way to what I rather (perhaps too) loosely called "optional" sleep, which maintains sleep until morning awakening. After about six hours of good sleep, all of core sleep has usually disappeared. "Optional" doesn't mean that we can dispense with it overnight, but rather, it is much more adaptable than is core sleep - so maybe I should now call it "elastic" sleep. My problem over the importance of REM sleep is that it can be removed entirely from sleep, for many months at a time, by medicines commonly used for treating depression, and without ill effects or any sign of big rebounds of REM sleep when treatment ceases. This refutes any idea that REM sleep is essential to memory processing, especially as dolphins have no REM sleep whatsoever, and are very intelligent animals. As so much of REM sleep seems to be dispensable, I don't see it as real sleep, as is non-REM sleep, but as "non-wakefulness" - even as a substitute for wakefulness, particularly in the baby before birth and for a few months afterwards.

Dreams

Dreams are simply to keep the brain periodically occupied during sleep - they are very entertaining, but only the "cinema of the mind". We dream as we think, and they are a fascinating jumbled distortion of recent events and thoughts. Thus the only person that can really figure out what the dream might mean, is ourselves. Dream dictionaries and so-called interpretations by others are figments of their imaginations not ours. Although for Freud dreams were the "royal road to the unconscious" this was stated at a time when society discouraged people from expressing their true selves and emotions, and maybe dream analysis was the only way of approaching a troubled mind. Nowadays, in our more enlightened society, we can get to the deepest recesses of the mind by establish rapport and talking to people at depth, when they are awake, rather than waste time in analysing their dreams.