EDITORIAL

The Need To Sleep

by CHITA C. HEAP

Sleep is something we take so much for granted. It seems bizarre that we sleep but do not fully understand why we sleep. What is sleep for? It is not just human beings who cannot do without a daily shut down; all mammals, birds, reptiles, amphibians, some fishes and invertebrates and even microbes appear to need a period of almost total inactivity at least once a day.

There is no doubt that whatever it is for, sleep is as necessary for life as food and water. Indeed, one of the most effective methods of torture known is sleep-deprivation; whilst some people can withstand seemingly infinite levels of pain without “cracking’, seven days of enforced wakefulness leaves almost everyone a gibbering wreck and there is no evidence of anyone surviving more than 11 days in this state.

So why do we sleep? The obvious answer: the body needs to rest after an arduous day, does not really add up. While we will certainly feel more tired after a very active day than one spent on the sofa, our absolute need for sleep does not change depending on how much energy we are burning.

The body is perfectly capable of maintaining itself “on the run” and other popular explanations-that we sleep at night to keep out of the reach of predators or because at night there is little an animal with poor night vision can do, does not fully answer the question either. Nocturnal hunters such as lions, sleep mostly in the day. While they may be more effective predators at night, they are capable of killing when  it is light.

Although nearly all organisms experience a “circadian rhythm”, dictated by the twenty four hour cycle of night  and day, true sleep is the preserve of animals with brains. And most experts believe that it is mental processes rather than tired muscles that are the key to understanding this most mysterious phenomenon.

One idea is that sleep acts as a kind of reset button, allowing our brains and nervous systems to recalibrate in peace. People with severe sleep disorders are more likely to suffer from irregular heartbeats, for instance.

Sleep may, it has been suggested, be a way for our memories to be consolidated and laid down. Dreams may act as a sort of screensaver for the mind, creating a distracting series of entertainments for a mind that is, in what amounts to an altered state of consciousness while memories and thoughts are processed.

Dreams, a key feature of human sleep (and probably all other mammals too) are as mysterious as sleep itself. For decades, the idea that dreams “mean” anything was dismissed by mainstream psychologists. But now the role of dreams is being taken seriously, not only as a method of organizing the memory but also as a way to improve mental health.

In 2009, Austrian scientists found that “lucid dreamers”, people who were able to take some conscious control of their dreams while asleep, reported significantly fewer psychiatric problems than non-lucid dreamers, and numerous studies have shown that dreaming can be an effective way of improving and honing cognitive skills and dealing with stress.

All animals sleep, but it is notable that creatures who live in large social groups, such as human, dogs and baboons, seem to need more sleep than most. It may be the case that we need to take time out from the tribe as a form of enforced social isolation in order for our brains to carry out the vital unconscious tasks of working out  their place in the social pecking order.

Did you know? A) Time slows down when you dream. Studies of lucid dreamers indicate that dreamed task take longer when asleep than when awake. This contradicts the popular notion that a whole lifetime’s worth of activity can be packed in to a few minutes of sleep.

B) That playing a musical instrument is one of the best ways of developing the ability to control your dreams.

C) Microbes sleep, or at least exhibit a distinct circadian-rhythm a daily cycle of activity and inactivity. Sleep is thus as old as life on Earth itself-more than three billion years.

D) Some animals can be literally half awake; dolphins are able to sleep one half of their brains at a time, a useful skill for a marine mammal that must return   to the surface to breathe. /MP