Sleep is necessary to life. However, it remains shrouded in mystery, despite the fact that most people spend one third of their lives asleep. At the end of the eighteenth century, Georg Christoph Lichtenberg (a scientist and amateur philosopher) mused on this enigma. ‘Why can we not wean ourselves from sleep?’, he asked. After all, the ‘most important functions of life’ – the beating of hearts and the circulation of blood – ‘never rest or sleep’. The process of sleep, therefore, must entail ‘a relaxation of the organs of thought’ more than anything else. In sleep, Lichtenberg concluded, people become ‘mere plants’, thus enabling them to fulfil God’s aim in making human beings ‘the masterpiece of creation’, the only true possessors of reason. Isn’t it remarkable, he noted, that ‘history contains only accounts of waking people’. Shouldn’t we be paying as much attention to the history of humanity at sleep as we do to their waking life?
It was a good question. After all, throughout history, philosophers and scientists have expressed curiosity about what happens when people close their eyes at night, but the ways in which sleep has changed over time has been relatively neglected. This is surprising. As a culturally learned practice, the forms and rituals of sleep vary dramatically. A person’s quantity and quality of sleep is different if she lies down on a flea-infested bag of straw or can afford to invest in cotton bedclothes and metal bedsteads (introduced in the late eighteenth century) or spring mattresses (available from the 1850s). The degree of privacy achieved has also shifted over time. In pre-modern Europe, it was common for all members of the family, boarders, and other visitors to sleep in the same room, and often the same bed, irrespective of age or sex. The individualization of sleep – with each person allocated a separate bed or even bedroom – only became common from the nineteenth century.
Sleep came with many risks. When homes were lit by candles made of tallow or beeswax (for those wealthy enough to afford them) or rushlights and candlewood (for poorer families), people regularly burnt to death at night. Unpaved roads and excrement (that would be thrown from windows) made the dark dangerous. In medieval Europe, wolves attacked and devoured thousands of people each year. Darkness also served as a cover for human-wolves, including thieves, rapists, and murderers.
Sleep is also profoundly political. From the vagrants of the nineteenth century to homeless refugees in the twenty-first century, sleep can be a rare commodity. In public parks, benches are designed to be as uncomfortable as possible for people ‘sleeping rough’ and refuges often kick their residents onto the streets as soon as the sun rises. In other contexts, the denial of sleep is a powerful weapon. Sleep deprivation is a well-honed method of torture employed by authoritarian regimes, including in Northern Ireland, Greece, Turkey, Israel, Jordan, and, more recently, in Abu Ghraib and Guantanamo Bay. Sleeplessness is a weapon of war against marginalized peoples and politically dissenters everywhere.
Given the powerful cultural role played by sleep and sleeplessness, it is hardly surprising that it has been understood in diverse ways in the past. In medieval theology, for example, the night belonged to evil spirits, ghosts, and human-animal chimeras. Escaping such dangers through sleep was not wholly possible. After all, these religious texts claimed that sleep itself was divine punishment for original sin. Sleep was a reminder of human imperfection and distance from God. It was risky since, while asleep, the human soul became vulnerable to invasion by evil spirits or even by the devil himself. Nightmares were often proffered as evidence of these dangers. In the eighteenth century and earlier, terrifying midnight reveries were understood to involve some kind of communication with the ‘other world’. Might they be the result of devils pressing upon the sleeper’s chest? They might even be evidence of the workings of black magic. And what if a person died while asleep? Might they be unprepared to meet their Maker? Closing one’s eyes in prayer prior to closing them in sleep made perfectly good sense.
Of course, not all dreams were nightmares – which is fortunate given than we spend ten per cent of our lives dreaming and the average person has between 100,000 and 200,000 dreams in his or her lifetime. Dreams could be positive. In many cultures (including among the Inuit of the Arctic regions), dreams occurred when the shadow component of a person left the body to travel to the land of death; it was a form of communication from the heavenly sphere to the mundane one. Dreams were often viewed as proving guidance on how a person should live. In the sixteenth century, for example, young women who slept with an onion under their pillows would dream of their husband-to-be; elsewhere, a piece of cake under a pillow procured sweet dreams. Delightful dreams were nothing short of the whisperings of angels.
Even people who scorned such mystical ways of thinking about sleep recognised that it came fraught with moral meaning. Excessive drowsiness was morally suspect. In the words of the Proverbs of Solomon (chapter six, verses nine to eleven):
How long will you lie there, you sluggard?
When will you get up from your sleep?
A little sleep, a little slumber,
a little folding of the hands to rest—
and poverty will come on you like a thief
and scarcity like an armed man.
Or, as a common aphorism put it, ‘Nature requires five, Custom takes seven, Laziness nine, And wickedness eleven’. People like Leonardo da Vinci, Napoleon Bonaparte, Voltaire, and Winston Churchill who claimed to require much less sleep than ordinary mortals were viewed with awe.
It is not only the total hours of sleep whose meanings is debated. How people sleep varied. In monophastic sleeping cultures (common in Northern Europe and the USA), it is generally assumed that people should take one period of sleep every twenty-fours hours. This is in contrast to biphasic sleeping, where siestas are routine, and polyphasic sleeping cultures (such as China, Japan and India), where naps are encouraged.
However, even monophastic sleeping cultures turn out to be historically contingent. In fact, sleeping in one block of time is a relatively recent phenomenon. Before the mid-eighteenth century, most Europeans divided their sleep into two distinctive periods. Their ‘first sleep’ would be followed by an hour or more of wakefulness, before resuming their ‘second or morning sleep’. The time in-between the ‘two sleeps’ was spent praying, calmly reflecting on life, chatting with family and friends, visiting taverns, completing domestic chores, or having sex.
This pattern of divided sleep began breaking down with the introduction of gas lighting from the late eighteenth century, coupled with the imposition of new codes of labour discipline associated with industrialisation. When Thomas Edison (who famously required only three to four hours sleep a night and castigated people who needed more for being unhealthy and inefficient) invented the incandescent light bulbs, which first illuminated New York streets from 1879, ‘modern’ patterns of sleeping were further encouraged. As a result of artificial lighting, people began to live between one-third to one-half of their lives in environments that were radically different from their recent ancestors.
In the 1990s, however, sleep researchers discovered something extraordinary: the ‘two sleeps pattern’ is more ‘natural’ than the ‘one block of sleep a night’ that most people practice. This research was pioneered by Thomas A. Wehr, psychiatrist at the National Institute of Mental Health at Bethesda (Maryland, in the U.S.). In an experiment involving a group of healthy men, he recreated light conditions that existed prior to artificial lighting. Within a few weeks, the men had reverted to the two-shift pattern of sleeping: they slept in two sessions of four hours each, separated by between one and three hours of ‘quiet wakefulness’. Blood tests revealed that in the interval between their ‘two sleeps’ their brains were producing high levels of prolactin, the hormone that reduces stress and is responsible for the relaxed feeling after orgasm. Having eight hours of unbroken sleep a night may not, in fact, be normal at all.
Twenty-four hour light – whether bright, direct light or the constant dull glow that pervades urban environments – changed not only our physiological sleeping patterns, but culture as well. Prior to artificial light, poor people and other members of the underclass were free to roam the streets. Gas and electric lights reduced their autonomy since towns and cities became considerably easier to police. Gradually, the sense of sight was prioritised over hearing. At the same time, however, what people saw could be more impoverished. Most notably, city-dwellers were denied the full magnificence of the night sky. Today, many people don’t even know what the sky looks like without light pollution. Shockingly, in 1994, when an earthquake knocked out electricity in Los Angeles, locals panicked when they noticed a strange ‘giant, silvery cloud’ in the sky: they were seeing the Milky Way for the first time.
The frightened people of Los Angeles should have taken the opportunity of profound darkness to get a good night’s sleep without the constant glare of light and the buzz of electricity. Instead, the darkness just made them sleepless. According to the ancient Egyptians, one of the three living hells was ‘to be in bed and sleep not’. It was Democritus, however, who in 420 BC identified sleeplessness as a sign of ill-health or disease. It is no wonder that, since ancient times, considerable cultural labour has been put into the problem of insomnia. Ingenious spells, elaborate chants, and complex rituals have been proposed to help people fall asleep. In ancient and medieval times, for example, people were so desperate to doze off that they brushed their teeth with the earwax of dogs, rubbed the fat of dormice onto the soles of feet, and drank a concoction made from the gall of a castrated boar.
Modern interventions are no less ingenious. From the 1970s, sleep clinics proliferated. Inventors have designed mattresses, pillows, and an array of apps to induce sleepiness. Pharmaceutical companies turned the problem of sleeplessness into a big business. They not only targeted common forms of insomnia, but also restless leg syndrome (described as early as the seventeenth century), narcolepsy (which was thought to be a form of epilepsy or a psychiatric disorder until REM sleep was discovered in the 1950s), and ‘shift work sleep disorder’ (which affects between five and twenty per cent of shift workers). These conditions are not only unpleasant for sufferers but have severe social consequences. People who don’t getting enough sleep are at greater risk of peptic ulcers, insulin resistance, coronary heart disease, and depression. Every year, when daylight-saving shaves an hour off our sleep, fatalities on the road increase by seven per cent. The nuclear accidents at Chernobyl and Three Miles Island, not to mention the Space Shuttle Challenger disaster, have all been linked to sleeplessness.
But sleeplessness is not the only problem: people need drugs to keep them awake as well. Everyone from the scholar swatting for her final exams to the surgeon in an under-staffed emergency ward of a hospital are popping pills and potions to keep awake. Control over sleep is particularly strong in the military, where disciplined bodies that are effective for incredibly long hours are essential. Night-vision goggles, thermal imaging systems, and laser range finders (to name just a few technologies) have made combat a 24-hour activity. Service-personnel are even given atropine and benactyzine to dilate their pupils in order to improve night vision. When the leading ‘go-pill’ Modafinil was first introduced in 1989, a spokesperson for the French Ministry of Defence defended its use on the grounds of the changing nature of modern warfare. He pointed out that ‘If there is a war in Europe, it will be very quick and will be carried out during the night as well as in daytime. Hence we need armies capable of maneuvering [sic] at any time for three or four days, non-stop, without diminishing performance’.
Concerns about a 24/7 culture are not restricted to warfare, though. In the twenty-first century, sleep has again become a major concern. Are we working too long? Have flexible schedules – often hailed as a godsend to working mothers – become another cause of exploitation? In information-rich work cultures, would performance levels rise if we did more napping? Are we paying too high a cost for structuring our lives around the clock as opposed to the solar day? Voltaire reminded us that ‘heaven has given us two things to counterbalance the many miseries of life: hope and sleep’. We need more of both.
Comentários