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

would compete for money. The rules were simple: keep dancing until you drop. This grisly social phenomenon was portrayed in the 1969 film They Shoot Horses, Don’t They? The dance-marathon competitors were supposed not to sleep, although some competitions permitted one dancer to sleep provided their partner held them upright and both kept moving. They must have slept while dancing, since it was not uncommon for these nightmarish marathons to last for weeks. The world record was set by a couple in Chicago, who danced from 29 August 1930 until 1 April 1931 – a total of almost 215 days. The rules allowed them to close their eyes for no more than 15 seconds at a time, so they must have been adept at sleeping with their eyes open. Their reward for this outlandish spectacle of public torture was a paltry $2,000. These dance marathons were eventually made illegal. And talking of torture, let us turn to that uncomfortable subject.

Uses and abuses

      It was always at night – the arrests invariably happened at night. The sudden jerk out of sleep, the rough hand shaking your shoulder, the lights glaring in your eyes, the ring of hard faces round the bed. In the vast majority of cases there was no trial, no report of the arrest. People simply disappeared, always during the night.

      George Orwell, Nineteen Eighty-Four (1949)

      Sleep deprivation is unpleasant and debilitating. Someone who has not slept for two or three days can feel as if they are losing their mind. That is why, throughout history, sleep deprivation has been exploited as a form of torture and coercion. Fatigue can bring people to their knees, both metaphorically and literally, without leaving a mark on them. It can even be fatal.

      According to legend, King Perseus of Macedonia was put to death by being prevented from sleeping when held prisoner in Rome. Sleep deprivation is also said to have been a form of capital punishment in China in times past. The American writer and insomniac Bill Hayes cites a nineteenth-century account of a Chinese merchant who was sentenced to death for murdering his wife. Sleep deprivation was deliberately chosen as the method of execution, on the grounds that it would cause the maximum amount of suffering and would therefore serve as the greatest deterrent to other potential murderers. According to the account, which was written by an American physician, the prisoner eventually died on the nineteenth day, having suffered appalling torment.

      Sleep deprivation has been employed for many centuries to soften up prisoners and make them talk. And it still is. Amnesty International found that more than half the torture victims they interviewed had been deprived of sleep for at least 24 hours. The secret police notoriously prefer to make their arrests in the small hours of the morningbecause that is when people are at their weakest and most confused.

      When applied patiently and systematically, sleep deprivation is said to be the single most effective form of coercion. The victim is repeatedly woken at odd hours, allowing them little or no sleep. The pattern of awakenings is randomised, so the victim loses all control over when they sleep (an extreme version of what happens to parents of small babies). This unpredictability makes it impossible for the body’s internal clocks to readjust. The circadian rhythms become disrupted, leaving the victim fatigued and in a state akin to severe jet lag. All sense of time and place depart. Even the strongest person can be reduced in this way to a state of helpless and tearful disorientation.

      Exhausted people are very poor at making sound judgments based on complex information, including information derived from their own knowledge, beliefs and experience. Sleep-deprived prisoners are therefore much more susceptible to persuasion that their actions or beliefs are wrong. Herein lies the secret of ‘brainwashing’.

      In the Korean War of 1950–53, the Communists tortured American and Allied prisoners of war by systematically depriving them of sleep. A constant succession of guards would interrogate a prisoner at random times throughout the day and night, subjecting him to a constant barrage of questions and arguments. The effects on prisoners’ behaviour and beliefs were often profound. Sixty per cent of the US airmen who were captured in the Korean War either confessed to imaginary crimes, such as using biological weapons, or collaborated with the enemy in condemning the USA. When the prisoners were eventually returned to the USA, the US government appointed a panel of experts to discover what had happened. The assumption at the time was that the Communists must have subjected the Allied prisoners to some mysterious and sophisticated form of mind control. Either that, or the men must be traitors and cowards. But the evidence uncovered by the review panel ruled out drugs, hypnosis or other forms of novel trickery. The truth was more prosaic. Just one device had been used to confuse and torment the prisoners until they were ready to confess to anything. That device was prolonged sleep deprivation. A combination of fatigue, confusion, fear and loss of control had produced profound changes in the men.

      The practice of sleep-depriving military prisoners continues to this day. In April 2001 a US military surveillance aircraft collided in midair with a Chinese fighter. The American plane was forced to make an emergency landing in China. Meanwhile, the Chinese plane crashed, killing the pilot. The Chinese authorities were not happy: they impounded the American plane along with its crew of 24, sparking a diplomatic row between the two nations. The crew were eventually released after being detained and questioned for 11 days. They later revealed that the Chinese had used sleep deprivation as part of the interrogation process. The American pilot reported that the Chinese had questioned him for several hours on the first night, and thereafter had repeatedly woken him at various times of the night and day, forcing him to snatch a little sleep whenever he could.

      Prolonged sleep deprivation lay behind many of the psychiatric casualties of World War One. Thousands of men had to be withdrawn from the horrific conditions of the front line with what was referred to then as shell shock. (Nowadays we would call it post-traumatic stress disorder.) Continuous shelling was undoubtedly a cause of severe stress. For hours or days at a time, men crouched defenceless in muddy trenches, constantly exposed to the threat of instant death or injury but powerless to do anything about it. Even the hardiest of minds could crack. But the shelling broke men for another reason as well: it prevented them from sleeping. Doctors often found that when a man with disabling shell shock was granted respite from the front line, he would rapidly recover and be able to return to his unit within days. Getting a few nights’ sleep in the hospital probably did more good than the psychotherapy that went with it.

      When we starve ourselves of sleep in the name of work or play, we go partway down a path that leads eventually to something horrific.

       4 The Golden Chain

      Sleep is that golden chain that ties health and our bodies together.

      Thomas Dekker, The Guls Horn Book (1609)

      We have seen some of the bad things that sleep deprivation does to our minds. What does it do to our bodies? Sleep and physical health are intimately intertwined, which means that inadequate sleep can cause all sorts of physical problems. When sleep deprivation is taken to the extreme, death ensues. Some scientists have argued that many of us neglect or mismanage our sleep to the extent that it damages our health, and that large numbers of people around the world die prematurely every year because of undiagnosed and untreated sleep disorders.

      What, then, is the scientific evidence that sleep impinges on our physical health? Some (admittedly crude) indicators point towards a link between poor sleep and poor physical health. For instance, people who are sleepy during the day are more likely to use healthcare. And older people who complain of poor sleep are at greater risk of a heart attack. One American study that tracked thousands of elderly people discovered that individuals with sleep problems were more likely to suffer a heart attack over the following three years.

      Lack of sleep and the resulting daytime tiredness are associated with greater sickness absence from work. An investigation of absenteeism among French employees found that those who reported feeling very sleepy at least three days a week were more than twice as likely to take sick leave as their less sleepy colleagues. Sleep problems are also