Counting Sheep: The Science and Pleasures of Sleep and Dreams. Paul Martin

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СКАЧАТЬ taken. The official report noted that ‘fatigue is not what caused the accident, but it didn’t help the decision-making process’. It also commented that ‘working excessive hours, while admirable, raises serious questions when it jeopardises job performance, particularly when critical management decisions are at stake’. Bear in mind that when official investigations search for the causes of disasters they instinctively focus on tangible, physical causes like rubber O-rings and air temperatures; intangible human factors like fatigue are seldom in the forefronts of investigators’ minds.

      Lack of sleep has contributed to, if not caused, a string of disasters and near disasters in nuclear power plants. Many of them occurred in the early hours of the morning – a common feature of sleep-related accidents – and stemmed from failures by human operators to make sensible decisions when faced with the relevant information. Research has confirmed that nuclear power-plant operators who work night shifts experience real problems with sleepiness, distractibility and poor alertness. Even if they are not particularly sleep-deprived, they are unlikely to perform well in the early hours of the morning. And that is when the accidents happen.

      The worst nuclear incident so far in the USA took place in March 1979, when the reactor at the Three Mile Island power station near Harrisburg in Pennsylvania came close to meltdown. The near-disaster at Three Mile Island arose in the early hours of the morning, after operators failed to recognise what their instruments were plainly telling them – namely, that an automatic valve had closed, cutting off the water supply to the coolant system. The reactor shut itself down automatically, as it was designed to do when a malfunction like that occurred. But a series of errors by the human operators led to a dangerous loss of coolant from the reactor core and almost turned an incident into a catastrophe. Radioactive gases were released from the partially exposed reactor core, but the containment vessel fortunately prevented them from escaping into the environment. Although no one died as a direct result of the Three Mile Island accident, it had a massive impact on the American nuclear industry. The damaged reactor took ten years to decontaminate and remained unusable. Fatigue is believed to have contributed to the operators’ repeated failures to handle the incident correctly.

      The worst nuclear accident thus far in history occurred at the Chernobyl nuclear power station in April 1986. It too was sleep-related, and started in the early hours of the morning when the operators were at their lowest ebb. The disaster happened when the engineers operating one of the station’s four nuclear reactors made a series of irrational judgments. They attempted an ill-conceived experiment that involved shutting down the reactor’s regulatory and emergency safety systems and withdrawing most of the control rods from the core, while allowing the reactor to continue running. The operators exhibited the alarming propensity to take inappropriate risks that is characteristic of tired people. As a later report put it, they behaved ‘like intelligent idiots’.

      The reckless behaviour of Chernobyl’s operators caused a chain reaction. At 1:23 a.m. on the morning of 26 April a series of explosions blew the reactor apart. There was a partial meltdown of the reactor’s graphite core and it caught fire. Large amounts of radioactive material were released into the environment – several times the amount created by the atom bombs dropped on Japan in World War Two. Some of it was carried by winds and contaminated several western European countries, including France and the UK. Thirty-two people at the Chernobyl plant died at the time of the accident and several more died soon after from severe radiation exposure. The long-term damage to the health of populations living in affected areas remains a matter of controversy, but it is undoubtedly huge. Several thousand people have died, or will die, as a result.

      Over and over again, man-made disasters like Chernobyl and Exxon Valdez have occurred at night or in the early hours of the morning, when people’s reactions and judgment are at their weakest. We saw earlier that drivers are much more likely to have a serious crash late at night than in the middle of the morning. Almost everyone who works night shifts displays signs of sleepiness and impaired performance, and it is not difficult to see why. Working at night forces people to perform at a time when their biological clocks are telling them to sleep, and to sleep when their biological clocks are telling them they should be awake. They perform worse when they are at work, and they are less able to sleep when they go home, as a result of which they become tired and accident-prone. Add chronic sleep deprivation to the brew and you have a potentially lethal concoction. And we all have to live with the consequences.

The price of eternal vigilance is liberty

      Care is heavy, therefore sleep you.

      Thomas Dekker, Patient Grissil (1603)

      If society were to recognise the true importance of sleep, then attitudes towards tiredness on the roads and in the workplace might become more enlightened. In a more sleep-conscious world it would no longer be socially acceptable, let alone admirable, for people to drive or turn up for work suffering from severe fatigue, any more than it is now acceptable to be drunk in the workplace or behind the wheel of a car. Napping during working hours would be tolerated and even encouraged, rather than stigmatised as a sign of sloth, drunkenness or illness. Meanwhile, society continues to turn a blind eye to people driving cars, flying aeroplanes, practising medicine, operating safety-critical machinery and running nations when they are mentally and physically impaired by lack of sleep.

      In the next chapter we shall see that sleep-deprived people are bad at making decisions and communicating those decisions to others. Their judgment is impaired, they are easily distracted, they respond poorly to unexpected information, they lack flexibility, they persist with inappropriate solutions to problems and they are prone to taking foolish risks. These are not the characteristics any of us would wish to see in the people who make life-and-death decisions in the corridors of power, hospitals, flight decks or nuclear power stations.

       3 Dead Tired

      You lack the season of all natures, sleep.

      William Shakespeare, Macbeth (1606)

      Does it really matter that many people in industrialised countries no longer get enough sleep of sufficient quality at the right times? We have seen one reason: the fact that sleepiness causes accidents. But far more than that, inadequate sleep matters because of what it does to our minds and our bodies each and every day.

      Sleep is eloquent in its absence. We know that if we miss a night’s sleep we will feel bad the next day. But the unpleasant sensations of acute fatigue evaporate after a good night’s sleep and we soon forget. Far less obvious are the insidious, cumulative consequences of seldom getting quite enough sleep, night after night, week after week. Chronic sleep deprivation creeps up on us. It has pervasive effects on our mood, social skills and mental abilities – especially judgment, creative thinking and problem solving. It can also impair our physical health and make us more vulnerable to disease, as we shall see in the next chapter. However, the first and most obvious symptom of insufficient sleep is sleepiness, and that is where we shall start.

Sleepiness

      Life is one long process of getting tired.

      Samuel Butler, Notebooks (1912)

      The longer you go without sleep, the sleepier you feel. Objective measurements prove that there is indeed a close relationship between sleep deprivation and sleepiness. That relationship is ‘dose-dependent’, which means that the longer you have been deprived of sleep, the faster you will fall asleep when given СКАЧАТЬ