Sleep is the state of the body that usually takes place for several hours every night where activity slows down in almost all organs except the brain. On the outside, it looks like the person has shut down because the muscles are relaxed, eyes are closed, breathing is slow and steady.
According to the Oxford Dictionaries, "consciousness is practically suspended" during sleep. On the inside, if the brain is disregarded, it also looks like the body is slowing down due to some systems becoming more inactive. However, we sleep for many reasons, including that it benefits our body and acts a bit like the conclusion of our day.
It's not just humans who sleep, but nearly every single living creature also sleeps or at least experiences something of the sort. In fact, many other animals can have dreams too. Sleep is a mysterious topic and although scientists have researched the basics surrounding the topic, some information including the exact reason people sleep is still unknown.
When a person is awake, we are in what's called a 'catabolic state' where more energy is used than saved. This is because people usually engage in some sort of activity of the mind or body and they require energy to do so.
When people are asleep, they’re in what's called an 'anabolic state' when the energy spent is less than the energy conserved because people do less since they spend the time lying down. This way, the only body processes taking place are usually internal.
During this state, the body focuses more on self-repair and growth. Many little things happen to our bodies when it is asleep such as the narrowing of the throat, growth hormone production and many more complex processes take place.
For some technical knowledge in a short video, visit https://www.youtube.com/watch?v=fNlp0UMqUtM
For a more normal-person-friendly video, visit https://www.youtube.com/watch?v=rMHus-0wFSo
Sleep is put into 4 main stages: 3 that are called Non-REM [NREM] and one that is called REM. Both types of sleep serve its own purpose. Each stage is different, they take place in a certain order and repeating once finished, forming a cycle which would repeat around 5 times each night. Each stage is important, playing its role throughout the night.
The first section of sleep is called N1 [stage 1] or ‘introduction to sleep’, it is relatively short: around 5 - 15 minutes . During this light sleep stage, the person has only just drifted off to sleep and is easily awakened by external factors. Many people experience a sensation of falling which causes them to jerk or ‘jump’ awake, called a hypnic myoclonia jerk. If a person is awakened during this stage, he or she may feel like they haven’t slept at all.
The second section of sleep is called N2 [stage 2] or the ‘beginning of true sleep’. Although there will be more difficulty to wake during this stage than stage 1, the person can become alert and awake quite easily. The person’s heartbeat rate and breathing will slow down, and their body temperature will decrease slowly
The third section of sleep is called N3 [stages 3 and 4] or ‘deep sleep’. The brainwaves here are the slowest, called ‘delta’ waves. The person’s breathing and heartbeat will slow even more so, the person’s muscles will become near completely relaxed.
This is the stage where most of the body repair and maintenance takes place: muscles are strengthened and built, growth is stimulated, tissues are fixed and replaced, the immune system is strengthened, and bones are built. If a person is awakened during these two deep sleep stages, he or she will feel disoriented and groggy.
The last main section of sleep is called REM sleep [rapid-eye-movement], it takes place around 70 - 90 minutes after the person has fallen asleep. The brainwaves during this stage are similar to the ones of a person awake [alpha waves], as this is the stage where dreams occur. The amount of blood that goes to brain areas linked to processing memories and emotional experiences increases, while there’s a decrease in the blood flow to areas of the brain that control complicated processes [such as reasoning, or language].
This stage of sleep is called ‘rapid-eye-movement’ because the person’s eyes during this time will move from place to place very quickly and randomly, scientists do not know why and are still researching this topic.
One such reason that many believe is the purpose of sleeping is for that day’s learning and memory processes. However because the research in this area is limited, and that the results from experiments on this soft science are mixed, not everything is certain.
There are many other theories such as the restorative theory. In the restorative theory, people and other living creatures enter the state of the sleep to rejuvenate themselves for the day ahead of them.
Sleep is essential as stated before, to all living organisms including microbes and plants. Without sleep, the creature will die, with little sleep, the creature will survive but their body will not be functioning properly.
in teens, the amount of sleep needed // recommended is 8.5-9.5 hours. in adults, it’s 7.5-9 hours. needless to say, it’s generally known the much of the population do not get this amount of sleep everyday.
A lack of sleep damages the body, and causes it to perform much less that it would if the body got enough sleep. It causes and contributes to many medical conditions, and the body functions weaken
Sleep deprivation takes a toll on the body in many different ways and in different intensities. If a person is awake for 17 hours straight, their performance would be decreased the same amount as if their blood alcohol level was at 0.05% [2 glasses of wine].
There are mounds and mounds of effects of lack of sleep. Here are a few:
nausea, dizziness, chronic migraines, feeling tiredness and exhaustion therefore a lack of motivation to do certain things
being easily irritated, moodiness, anxiety, tantrums and mood swings
having difficulty making decisions and/or making poor decisions because a sleep deprived prefrontal brain cortex cannot work properly
more frequent colds, infections etc
poor memory because the lack of sleep reduces nerve cell connections
reduced mental abilities such as creativity and problem-solving skills
If you need more incentive to get some more sleep, visit here: http://www.webmd.com/sleep-disorders/features/9-reasons-to-sleep-more
One tragic example of someone who got not enough sleep a 26-year-old man who went 11 days without sleep in an attempt to watch all the matches of the June 2012 European Cup. Because he was Chinese and lived in China, the times of the matches were during the night instead of day, so the man would work during the day and watch during the night. He also drank alcohol and smoked, however, on the eleventh day of watching, he died.
All in all, if all these factors are considered: of what sleep is, what it does for us, why we do it, and what might happen to us with too little of it, we can conclude that sleep is very very important. we need it for physical health. we need it for growth. we need it for mental health.
Here are more links for information:
http://ngm.nationalgeographic.com/2010/05/sleep/max-text
http://www.theatlantic.com/health/archive/2013/12/how-sleep-deprivation-decays-the-mind-and-body/282395/
https://hbr.org/2006/10/sleep-deficit-the-performance-killer