Counting Sheep: The Science and Pleasures of Sleep and Dreams

The supposedly robust adolescent is, if anything, even more vulnerable than older people. One study found that when youths aged 10–14 years were restricted to only five hours in bed for one night, their verbal creativity, verbal fluency and ability to learn new abstract concepts were all impaired. Less complex mental functions, such as rote learning, were unaffected by this modest degree of sleep restriction. So the sleep-deprived adolescent would still be able to go through the basic motions at school the next day, but would be unable to perform to anything like their true potential. And it is not entirely unknown for adolescents to go to school after getting less than a full night’s sleep.

As well as sapping our ability to perform, sleep deprivation also impairs our motivation. Tired people just can’t be bothered. In one experiment, researchers persuaded a group of male students to work continuously for 20 hours without sleep and then observed them in various social settings. Sleep deprivation diminished everyone’s performance, but the students who were working in groups performed even worse than those who were working individually. This was because working in a group gave them the opportunity to loaf – and they did.

Another alarming characteristic of sleep-deprived people, and something else they have in common with drunks, is their propensity to take risks. Experiments have shown that as people become more fatigued, they are more attracted by actions that might bring big rewards and less worried by the possible negative consequences of those actions. For instance, French scientists assessed the risk-taking propensities of military pilots who were involved in a maritime counter-terrorism exercise. This required them to make strenuous night flights, depriving them of sleep. The data showed that as the exercise progressed, the pilots became more impulsive. In effect, sleep-deprived people become more reckless and foolhardy. This is yet another characteristic that you would not wish to encounter in someone who is in charge of a hospital ward or a political crisis or a nuclear power station, or the family car for that matter.

Alcohol, beauty and old age

It provokes the desire, but it takes away the performance.

William Shakespeare, Macbeth (1606)

Tired people resemble drunk people in several respects. Most obviously, tiredness and alcohol both hamper our ability to perform tasks that require judgment, attention, quick reactions and coordination – such as driving a car, for example. Missing a night’s sleep has an impact on driving skills comparable to drinking a substantial amount of alcohol. In both cases safe driving is no longer possible; in one case, however, it is both legal and socially acceptable.

To compare the effects of sleep deprivation and alcohol, researchers persuaded healthy young men to drive a simulator while under the influence of varying degrees of sleepiness and with varying blood-alcohol levels of up to 0.08 per cent. (For comparison, the legal limit for driving in most countries is 0.08 per cent blood alcohol and in Scandinavian countries it is 0.05 per cent.) Alcohol undermined their ability to maintain a suitable speed and road position, and so did sleep deprivation. Drivers who had been awake for 21 hours (hardly a remarkable feat) performed as badly as drivers with a blood-alcohol level of 0.08 per cent. So, next time you miss a night’s sleep, try to remember (if you can) that your driving ability will be as bad as if you had a blood-alcohol level that would be illegal in most countries.

Recent research has underlined the parallel between tiredness and alcohol. Scientists assessed volunteers driving on a closed course, both after drinking alcohol and after sleep deprivation. Detailed comparisons showed that both acute sleep deprivation (one night with no sleep) and chronic sleep deprivation (two hours less sleep than normal each night for a week) caused impairments in performance and reactions that were almost indistinguishable from those caused by illegally high blood-alcohol levels. The inescapable conclusion is that even relatively modest sleep deprivation, of the sort that many people experience in everyday life, has potentially dangerous consequences. Shaving a couple of hours off your sleep each night for a week can make you as incapable behind the wheel as a drunk driver.

Another striking similarity between sleep deprivation and alcohol is that as well as impairing our performance, sleep deprivation also undermines our ability to realise that our performance has been impaired, as we shall shortly see. (Try saying that sentence quickly when you are tired or drunk.) Tired people, like drunk people, have a misplaced confidence in their own abilities. This dangerous trait was highlighted in an experiment in which students took cognitive tests after they had been deprived of sleep for 24 hours. Predictably, they performed worse than subjects who had slept well the night before. However, when asked to assess their own performance, the sleep-deprived subjects awarded themselves higher ratings than did the non-deprived subjects. Tiredness had marred their ability to appreciate their own inability.

Cultural attitudes towards being tired or drunk behind the wheel of a car are very different, despite the fact that the net outcomes are remarkably similar and sometimes fatal. Driving when drunk is illegal and (nowadays) socially unacceptable, whereas driving when tired is neither. People still boast about their feats of sleep-deprived driving, in the way that people once boasted of their ability to drive after downing stupefying quantities of booze. Of course, one big difference between drinking alcohol and going without sleep is that drinking alcohol is enjoyable. Sleep deprivation has only the bad bits to offer, including the hangover.

Being tired and drinking alcohol are obviously not mutually exclusive. Indeed, the two often go hand in hand. A night on the town is often a night of little sleep. What is more, they reinforce each other. Tiredness amplifies the effects of alcohol and vice versa. It is a common experience (except presumably among lifelong teetotallers) that alcohol packs a heftier punch when we are tired – say, at the end of a hectic working week. Even moderate amounts of alcohol produce a big sedative effect after insufficient sleep. Conversely, the effects of alcohol are somewhat blunted if you are well rested. Experiments have found that alcohol reduces the alertness of people who have had less than eight hours’ sleep the previous night, whereas the same amount of alcohol makes no difference if they have had unlimited sleep. If you want to enjoy a few drinks without wilting, make sure you sleep properly the night before.

Another common experience is that the effects of alcohol vary according to the time of day when it is drunk. This happens because alcohol reinforces our natural circadian rhythm in sleepiness, exaggerating the troughs in alertness that normally occur in the early hours of the morning and again in the afternoon. Alcohol consumed at lunchtime or in the early afternoon therefore tends to have a bigger impact than the same amount consumed in the early evening, when alertness is normally higher. Lunchtime boozing really is more likely to make you fall asleep at your desk or crash your car than those pre-dinner ‘sharpeners’.

Scientists have also uncovered some intriguing parallels between sleep deprivation and the normal ageing process. As we grow older, our performance declines on many psychological and neurological measures. A similar pattern of deterioration is observed in young people after sleep deprivation. One experiment found that after 36 hours without sleep, adults in their twenties had a performance profile similar to that of non-sleep-deprived people aged about 60. So, if you are in your twenties and you want to know how it feels to have the brain of a healthy 60-year-old, just stay up all night. Then you will know. The reason why ageing and sleep deprivation exert similar effects may be because they both impair the functioning of the prefrontal cortex, a region of your brain that is extremely active when you are awake.

To complete the three-way permutation, alcohol and old age make an unpleasant cocktail. Being old is generally bad for sleep, and so is being an alcoholic. Being old and alcoholic is even worse. The elderly are more prone to insomnia, as we shall see in a later chapter. Alcoholism is also accompanied by sleep problems. And when old age and alcoholism combine within the same person they reinforce their malign influences on sleep. Researchers have found that older alcoholics have significantly worse sleep problems than younger alcoholics.

Sleep, or lack of it, can also affect physical appearance – a belief encapsulated in the term ‘beauty sleep’. Although sleeping all hours will not necessarily make you more beautiful, prolonged lack of sleep will detract from your physical charms. Animals that have been experimentally deprived of sleep for long periods develop unsightly skin disorders. Lack of sleep in humans, especially adolescents and young adults, might exacerbate skin problems such as acne. Sleep deprivation weakens the ability of the skin to maintain its normal protective functions as a barrier against dirt and microbes. That said, the scientific evidence for a direct causal link between sleep and an unblemished complexion remains sparse, Sleeping Beauty notwithstanding.

Lack of sleep probably does contribute to the depressing tendency of men to become pot-bellied and flabby in middle age. In men (but not women) almost the entire day’s production of growth hormone within the body occurs during sleep. The less sleep a man gets, the less growth hormone his body produces. As part of the normal ageing process, the total amount of sleep and the production of growth hormone both decline in parallel. Scientists have suggested that this age-related fall in growth-hormone production could be responsible for the systematic replacement of muscle by flab, better known as middle-aged spread. If so, dwindling sleep might be an important ingredient in the expanding waistline, double chins and spindly legs that help to make male middle age such a joy.

Champion wakers

I’ll wake mine eyeballs out.

William Shakespeare, Cymbeline (1609–10)

What happens to people if they get no sleep at all for a long time? One of the first scientific experiments on sleep deprivation dates from 1896, when Professor G. T. W. Patrick and his colleague Dr Allen Gilbert of the Iowa University Psychological Laboratory kept three volunteers awake for 90 hours. Patrick and Gilbert charted the now classic signs of prolonged sleep deprivation, including progressive deteriorations in reactions, memory and sensory acuity, together with a decline in body temperature.

Their first experimental subject, an assistant professor at the university, suffered his worst fatigue during the second night. Like Charles Lindbergh, he found that dawn was the cruellest time. He experienced visual hallucinations in which the air seemed full of red, purple and black dancing particles like gnats. All three subjects gained weight during the experiment, but their muscular strength diminished as they became more fatigued. The most noticeable effects were on mental performance: their memory became highly defective and they lost their ability to pay attention. One subject failed to memorise in 20 minutes material that he would normally have committed to memory in two minutes. In all cases, the symptoms disappeared after the experiment.

The first person to become internationally famous for self-imposed sleep deprivation was an American disc jockey called Peter Tripp, whose other claim to fame was inventing the Top 40. In 1959, Tripp managed the feat of staying awake under supervision for more than eight days and nights, a total of 201 hours. He did it to raise money for charity. Tripp even managed to broadcast live during his marathon, from a booth in Times Square, New York.

Peter Tripp suffered. As time went on, his friends and invigilators found it harder and harder to keep him awake. Constant vigilance was required to prevent him from lapsing into microsleeps. Three days into the experiment, Tripp became abusive and unpleasant. After the fifth day he progressively lost his grip on reality and started to experience visual and auditory hallucinations. His dreams broke through into his waking thoughts and he began seeing spiders in his shoes. He became paranoid and thought people were drugging his food. At one point he ran into the street and was nearly knocked down. These disturbing psychological symptoms were accompanied by physical changes, including a continuous decline in body temperature. By the last evening, Tripp’s brain-wave patterns were virtually indistinguishable from those of a sleeping person, even though he was apparently still awake.

After 201 hours of continuous wakefulness Tripp had broken the record and halted the experiment. He immediately fell into a deep sleep that lasted 24 hours. When he finally did awake, his hallucinations had gone and he felt relatively normal. But something seemed to have changed within him. Those close to Peter Tripp felt his personality had altered permanently, and for the worse. His wife left him, Tripp lost his job and he became a drifter. Tripp’s marathon of sleep deprivation certainly did him no good, but it was probably not the sole cause of his subsequent decline and fall. Tripp was taking large doses of Ritalin, an amphetamine-like stimulant drug, to keep himself awake during the marathon, and it is possible that the drug, combined with the sleep deprivation, helped to stimulate his paranoid delusions and hallucinations.

A few years later, Tripp’s record was broken by a 17-year-old high-school student from San Diego called Randy Gardner. In 1965 Gardner stayed awake for 264 hours (or 11 days) in a successful attempt to break into The Guinness Book of Records. Scientists from Stanford University monitored most of his marathon. During the first two days Gardner’s friends helped keep him awake and he did not use caffeine or other stimulants. By the end of the second day he was suffering from blurred vision, making it difficult for him to read or watch TV. By the third day he was irritable and wanted to be left on his own. His speech became slurred and his movements uncoordinated. On the fourth day he experienced memory lapses and mild hallucinations. After nine days without sleep he was unable to complete sentences and had lost the ability to concentrate. On the eleventh and final evening he had double vision.

Despite these temporary but unpleasant symptoms, Randy Gardner suffered remarkably few ill effects. Having stayed awake for 11 days and nights, he went to bed and slept for nearly 15 hours. When he awoke he felt fine. The following night he slept only slightly longer than usual, and within a few days his sleep had returned to normal. He did not go mad and, except for mild hallucinations, he never displayed any psychotic symptoms during the experiment. The experiences of Randy Gardner and others have demonstrated that going without sleep for several days does not generally result in mental illness or other long-term damage.

Some feats of self-imposed sleep deprivation have been endured for purely financial reasons, with not a single scientist in sight. In the depression-era USA of the 1920s and 1930s, a bizarre fad developed for dance marathons, in which people 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 predictive of long-term work disability. Norwegian research found that adults who were experiencing mediocre or poor sleep were more than twice as likely to face long-term work disability a few years later. People who sleep badly also tend to eat badly, which may contribute to their health problems.