Why do humans need to sleep?
Mark from Stoke on Trent (age 25-34)
Why do humans have to sleep and will we be able to eliminate the need for sleep?
Katie Edwards from Greater London (age 25-34)
Why do we need sleep and what is it?
Rebecca James from County Durham (age: 5-14)
Why do you get sleepy???
Laura Gale from Swansea (age 5-14)
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.
Jim Horne, Professor of Psychophysiology and Director of the Sleep Research Centre at the University of Loughborough