Regular FeaturesTake a Break
Sleep: what we all do, but don’t think much aboutWhy we sleep, why we should sleep, and how we should sleep
Kim Ji-sun  |
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승인 2014.11.06  01:09:05
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IT IS known that humans spend about a third of their entire life unconsciously, that is, sleeping. Considering the average lifespan of human beings, this means a typical human would spend approximately 25 years “shut down.” It may seem like a huge waste of time, said Thomas Edison, considering the fact that humans are mortal therefore destined to live a limited amount of time and eventually die. Even so, sleep is crucial to our lives. According to the National Sleep Foundation (NSF), sleep is essential for a person’s health and well-being: it not only helps our brains work properly, but also plays an important role in our physical health. Despite such predominant importance, we only know intuitively about sleep. So what more should we know about it?


Why do we fall asleep?

   One of the first theories regarding sleep came from Alcmaeon, a Greek writer. According to Alcamaeon, sleeping was a result of the flow cycle of blood: when blood is carried away from under our skin to our core, we would fall asleep until the direction of the flow is reversed, that is, the blood flows back from our core to our skin. Then Aristotle claimed sleep was tied closely to digestion: we would fall asleep until the act of digestion was complete. Despite numerous theories about sleep including those two, we now know that sleep is a result of several chemical reactions and bodily functions in our body.

   First of all, our internal body clock defines our daily bodily rhythm, which is therefore responsible for putting us to sleep. Synced with certain cues of the environment such as the amount of light, our internal clock lets our body respond to the environment, mainly chemically. In accordance with the surrounding environment, the clock lets us secrete or reduce several chemicals in our brains, namely adenosine, melatonin, acetylocholine, and cortisol, which are chemicals that induce sleep. First with adenosine, the level of this chemical continues to rise while we are awake, and puts us to sleep when a certain amount of the chemical is accumulated. Once we are in sleep, the reverse would happen: the body breaks down the compound, reducing the concentration of adenosine in our body, and we would slowly wake up again. When it gets dark, melatonin is released which makes us feel drowsy therefore signals our body of the need to sleep. Also, the level of acetylocholine in our hypothalamus, a portion of our brain that is responsible for hormone production, drops naturally which also induces us to sleep. And finally, cortisol, a steroid hormone that is closely related to bone formation and inflammation, is released at last in response to a low glucose level to wake our body up in the morning, which is also called the “cortisol awakening response.”


Why should you sleep?

   It is known that people can only live up to 11 days without sleeping: this surely proves how crucial and important sleep is for human’s well-being. The hours of sleep needed vary from people to people, in regards to factors like age and lifestyle. Even so, it is recommended that an average adult sleeps about 7 to 9 hours.

Sleeping 7 to 9 hours improves daily awareness and health. To begin with, simply sleeping enough improves our learning capabilities and productivity, while it also decreases our reaction time, making us less vulnerable to our surroundings. As for the healing power of sleep, sleep not only repairs our hearts and blood vessels but also stabilizes our immune system for better defense and more efficient response against harmful substances.

   Perhaps therefore it may not be surprising to learn that sleeping less than 7 hours each night in fact even reduces our life expectancy. It jeopardizes our body into 12% higher risk of premature death, 45% increase in risk of a heart attack, and a staggering 250% higher risk of diabetes according to the journal, *Sleep*, a research conducted by the University of Warwick. Also, lack of sleep may contribute to increase in weight of 0.9kg in under a week. Moreover, it causes parts of our brain to slow or shut down resulting in one or more of the several effects: slower thought processes, lack of focus, blurred vision and slurred speech.



·         Back pain

·         Headache

·         50% greater risk of diabetes

·         21% more likely to become obese


·         Lack of sleep was a factor in the many disasters in history: the Chernobyl incident, Exxon Valdez oil spill, 1979 nuclear accident at Three Mile Island, etc.


Steps to healthy sleeping

   So how can we prevent all these things from happening to us? The answer may seem like a cliché but the best solution is to sleep the recommended hours. For a sufficient sleep of 7-9 hours nightly, it is important to establish a healthy natural rhythm. You will be surprised at how much the simple act of getting up in the morning when it is bright, and going to sleep at night when it is dark will drastically increase the quality of your sleep. Turning off distractions such as cellphones and TVs before sleep, and taking a bath or drinking a hot cup of milk or tea will also help you fall asleep more naturally. It will heat up your body and slowly cool down which will help you feel relaxed and drowsy. This may sound a bit ironic considering the fact that keeping your body warm will help you fall asleep easier, but keeping the room cold at around 18,will also have the same effect. It is known that temperature around that range will decrease core body temperature and induce sleepiness.

   Simply increasing light exposure during the day such as avoiding the use of sunglasses, spending more time outdoors and having more daylight exposed to your room will also help. Or even better, just go to sleep when you are truly tired. Moreover, believing you have slept well, even if you have not, improves performance. Mind control will go a long way.


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Some remaining interesting facts about sleep

   The topic of sleep is very interesting. Here are some of the facts that make sleep such a fascinating topic:

·         Humans are the only mammals that delay sleep by will.

·         According to a recent study, people experience better sleep during the new moon and worse during a full moon.

·         There are actually many companies that promote napping as they believe it will improve the productivity of their workers. Those companies include *Google*, *Nike* and *British Airways*.

·         An experiment conducted in 1998 found that a bright light shone on the backs of human knees may possibly contribute to resetting the brain’s sleep-wake clock.


*                 *                 *

Sleep - as marvelous and mysterious as it is - it is also crucial to our mental health and well-being. Contrary to the frequently used phrase, it seems like “sleep ain’t for the weak” after all. This month’s article from the “Take a Break” section would like you to put your textbooks down, tuck yourself in your bed, close your eyes and “Take a Break”.



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