For many, there is nothing so beautiful as a refreshing sleep. There is perhaps no better description of sleep than that of Cervantes, who in his novel Don Quixote exuberantly sang of its praises with the passage, “Now, blessings light on him that first invented sleep! … it is meat for the hungry, drink for the thirsty, heat for the cold, and cold for the hot”. Such an encompassing illustration leaves nothing out of the picture, and should leave no room for doubt on the quality and benefits of sleep. Sleep is one of those things which is almost impossible to describe or identify, yet still is surprisingly simple. While sleep has changed much during the course of history, it still holds some of the most interesting treasure troves of information known in the natural world.
Our prehistoric ancestors, while perhaps not sleeping as much as the much-purported standard of 8 hours a day, nevertheless managed to fit in around 6 hours of high-quality sleep into their everyday lives. Their sleep habits are perhaps surprising to a modern viewer – in addition to the seemingly insufficient sleep time, research suggests that they did not take naps, slept more during the winter and less during the summer, and instead of going to sleep in accordance with the Sun, waited a bit more than three hours after sunset to begin their rest (they still woke at sunrise).
Later, as civilizations progressed and centuries passed, biphasic sleep started to enter the picture, especially as ancient communities moved north into Europe. As the Middle Ages drew to a close, people would use the time in the middle of the night between sleep segments to pursue leisurely activities, which mostly consisted of reading, praying, or even visiting friends. However, this new type of sleep would have a relatively short life, fading away as sleep returned to a single interval of time during the Enlightenment.
During the Enlightenment, a time of radical thinking and new scientific discoveries, sleep returned to a single phase. Data that Swedish researcher Olaf Hiorter collected on his own bedtimes and rise times still show the seasonal trend of prehistoric times; on average, he woke up an hour before sunrise during the winter and an hour after during the summer. Only after the introduction and proliferation of light technology in the late 1800s has the human sleep cycle become as unnatural and unchanging as it currently is. Artificial lights, and especially LEDs, interfere with the brain’s melatonin regulation, which as a result causes disturbances in circadian rhythms (a cycle occurring every 24 hours, normally regardless of light) and sleep cycles.
As the Industrial Revolution took its course, sleep became even more of a rarity, what with long hours and a six-day week. Sleep even became somewhat of a luxury. It was also during this time that striking workers clamored for an eight-hour workday, claiming that each day should have “eight hours for work, eight hours for rest and eight hours for what you will”.
All of this information on how sleep patterns have evolved begs the question of why sleep is even necessary. While it might be easy to simply accept this, along with the everyday functions of eating and breathing, as a fact that is (the squirrels do it, and those bears even sleep the entire winter, so why shouldn’t we?), there are many theories as to why both humans and other organisms need sleep (interestingly enough, while bacteria lack a spinal cord and are thus not able to experience sleep, they still implement a circadian rhythm for such processes as photosynthesis).
Extensive research has led to the proposal of four major theories as to why sleep is required – the inactivity theory, the energy conservation theory, the restoration theory, and the brain plasticity theory. While none of these theories is able to fully explain why sleep is an indispensable part of our lives, together they provide a reasonable explanation for why most organisms require conventional sleep (some of those which don’t include bullfrogs, honey bees, and dolphins). All of these theories also serve to highlight the cruciality of sleep.
The inactivity theory is based on Darwin’s evolutionary principles. Animals that were inactive during night were less likely to be eaten, and as a result, humans that possibly slept during the day gradually died out as a result of natural selection. The energy conservation theory, which also branches off of evolutionary theory, claims that sleep is a time to decrease metabolic functions and thus to increase the efficiency of hard-earned calories from hunting and gathering. Since both hunting and gathering were terribly inefficient during the nocturnal hours, this became a natural evolutionary solution. In fact, the body does slow down its metabolic function during sleep by as much as 10%.
The restoration theory, which is the idea that cells are repaired during sleep, stems from the idea that the body is unable to heal itself as effectively while awake since energy is being diverted towards other activities. Indeed, ample research has shown that muscle growth and repair, protein synthesis, and hormone distribution occurs much more frequently during sleep. Lastly, the brain plasticity theory says that sleep is a time for the brain to grow and develop while neurons reorganize. This theory helps explain why younger children, especially infants, require more sleep.
Dreams are another intriguing component of sleep. Most of the suggested reasons for why we dream include the proposition that dreams are a time for the brain to process and store information. Some even say that dreams are simply a by-product of other brain functions and have no meaning at all. No matter what dreams really are or what they’re really for, they have sparked countless discussions both about their meaning and their essence. In one remarkable story, the German chemist August Kekulé visualized the shape of the celebrated benzene ring after a dream in which he saw an ouroboros, a snake eating its own tail. Other celebrated intellectuals have also come across astounding breakthroughs while dreaming – Einstein’s dream of going down a hill at the speed of light while stars moved around him helped him develop his theory of relativity, while Ramanujan was able to see elliptical integrals in his dreams. While they may not be useful in the end, dreams might still just be the best part about sleeping.
Unfortunately, in today’s modern world of long hours, whether at work or at school, and electronic devices, being able to get a good night’s sleep is as hard as ever. And this can lead to serious consequences – knowing how important sleep is for the health of both the body and the mind, a lack of it has the potential to be disastrous. A perhaps not-so-shocking statistic puts the proportion of US adults who do not get enough sleep on a daily basis at 1 out of 3. Additionally, 40% unintentionally fall asleep during the day at least once a month, while an estimated 50 million have some sort of ongoing or chronic sleep disorder.
Sleep deficiency is particularly concerning because it lowers your brain’s ability to function – not only has your brain not recovered enough to function, but it is also struggling against the urge to sleep. As a result, sleep deprivation causes lower productivity (staying awake to heighten productivity in reality causes the opposite in the long term), interferes with life (work, school, everyday activities like commuting, and social matters), and leads to problems focusing, reacting, reading other people’s emotions, and staying unfrustrated. It has also been linked to multiple chronic health problems and tragic accidents – investigations of the likes of nuclear meltdowns and plane crashes reveal, perhaps unsurprisingly since workers at both jobs are not expected to sleep enough, that a lack of sleep was largely to blame. In children, who need sleep the most, sleep deprivation causes a decrease in learning ability and an increase in misbehavior.
Not getting enough sleep and then attempting to counter the adverse effects with caffeine, which functions by blocking adenosine detectors in the brain, might lead to a cycle of sleep deprivation, as caffeine makes you even less likely to fall asleep. Another cause for sleep deprivation is insomnia, a difficulty in falling or staying asleep and caused by a myriad of triggers which include depression and a lack of exercise.
One of the best problem-solving techniques is not to go after the problem, but instead the cause. In this case, instead of endeavoring to mitigate the effects of a lack of sleep by drinking coffee or staring at a bright screen, it is much healthier to try and get a higher-quality sleep in the first place. One proven technique to sleeping better is to be consistent, since letting your body get into a cycle will make both falling asleep and waking up easier. Another slightly obvious one is making your room more comfortable to sleep in, whether this means making it quieter or adjusting the temperature to suit your tastes. Electronic devices should also be removed to eliminate distractions to sleep. A healthy dose of exercise during the day helps too – letting your body become naturally tired through working out moderately lets you fall asleep easier. Lastly, avoiding large meals, alcohol, and caffeine before bedtime helps avoid problems falling or staying asleep. If one of the obstacles to getting enough sleep is time, while finding ways to make more time for rest may be challenging (and for students almost impossible), even small changes can bring about long-term benefits.
Sleep is a mystery that is as beautiful as it is elusive. Fortunately, no understanding of it is required to sleep well and let both your body and mind recover from the toils of a day or hard work and relaxation. As the old saying goes, good night, sleep tight, and don’t let the bedbugs bite.