O sleep, the certain knot of peace
There is ample evidence that a full night’s sleep is essential to maintain a healthy mind and body. There is, however, a school of thought that maintains that sleep is a luxury sought by the constitutionally lazy individual. Many people are convinced that neglect of proper sleep — sleep of the right quality and at the right time — lies at the root of many of our personal and social problems.
In the 27 October 2005 issue of Nature there is a discussion of sleep, its nature, its demands, the penalty for its neglect and how we should think about it. An editorial comment points out that the notion that successful people can struggle through life with little sleep adds to the misperception that hours spent in sleeping are wasted. There are serious ramifications. The past century has seen a tendency in industrial countries to reduce the time spent asleep by some 20 per cent. In the first place, this trend seriously threatens public safety, particularly through its repercussion on travellers and those given control of machinery. The National Science Foundation in the US has found that more than a third of American car and lorry drivers admit to having dozed off behind the wheel, and oil-tanker navigators denied proper
sleep have caused catastrophic accidents. In general, lack of adequate sleep has been linked to mood swings, mental depression, anxiety and other conditions affecting the thinking process. It is claimed that the medical profession as a whole has been slow to acknowledge the phenomenon, although three quarters of patients seeking help have a problem with sleeping patterns.
Sleep is much more than an absence of activity in the body and brain. Indeed, the brain remains highly active, especially in that part of sleep characterised by rapid eye movements and vivid dreaming. Sleep has many different stages, which take distinct forms. Falling asleep is often conceived as a gradual process but in fact the transition from waking to sleeping can be extremely rapid.
A neural switch in the brain hypothalamus brings about transitions between sleeping and waking, and damage to this region may induce instabilities in both sleeping and waking states.
The question of why we sleep at all has never been satisfactorily answered. It has, obviously, a close connection with the circadian rhythms that do much to regulate our habits. Since older persons sleep about half an hour a night less than younger ones, some of their cognitive decline and increased liability might be attributed to sleep restriction. Sleep loss might also affect adolescents having to rise early to travel at school, as it does overnight truck drivers and some hospital workers.
Consumption of stimulant or depressant drugs at certain times of day, either of necessity or choice, plays an important part in altering sleep patterns and should be taken into account. Even reading a book last thing at night may have remarkable effects.
Meanwhile, we might remember a sonnet of Sir Phillip Sydney (1591) in which he remarks: “Come sleep. O sleep, the certain knot of peace / the baiting place of wit, the balm of woe”. Sleep truly is a wonderful experience.
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In the 17 November 2005 issue of Nature, Andrew Robinson has commented on the multifarious activities of Thomas Young, an individual who could not resist investigating nearly every scientific question he encountered during his lifetime. His range of interests and his farsightedness have been particularly admired by physicists, physiologists and Egyptologists.