Bertrand Russell once wrote that, "men who sleeps badly are always proud of the fact."
The Science of Sleep
he Internet never sleeps but do you? The benefits of a good sleep has always been underrated. Sleep is one of the basic and yet strangest thing we do each day. But still many people are sleep deprived without knowing it. Think of this article as a guide that will walk you through eveything you know about the science of sleep. This article is inspired by a book called 'Why We Sleep' by Matthew Walker.
Before we move furthur, I have got something to ask you. Do you think that you got enough sleep the past week? Can you recall the last time you woke up without an alarm clock and feeling refreshed without consuming caffeine? If the answer to either of these questions is "no", then you are not alone. Sixty-five percent of people across all the developed nations do not obtain sufficient sleep and its highly unlikely that you believe it. But I am pretty sure that you will be shocked by the consequences of not getting the recommemded eight hours good night sleep.
~ Matthew Walker, Why We Sleep
The sleeping pattern differs from person to person along with their 'circadian rhythm'. Some people are morning larks and some are night owls. The so-called 'modern economic environment' is terrible for getting good night sleep. Bright lights, electronics devices, bigger screens and late-night weekends diminishes your sleep ability. In short, every single part of your body is influenced and enhanced by sleep. This is not a hyperbole.
The Circadian Rhythm
It is no coincidence that our brain keeps us alert or tired according to the time of the day. That means there's some kind of internal biological clock sitting in the middle of our brain which signals what time it is. Since the birth of this planet, the sun has always risen at dawn and set in the evening without failing and is one of the forces that drives sleep. And not just humans have adopted this circadian rhythm but many other creatures also obey the law. Adopting a circadian rhythm means to synchronize themselves and their everyday activities, both internal (for e.g., temperature) and external (for e.g., feeding) with daily orbital mechanics of planet Earth. The biological 24-hour clock sitting in our brains is called the 'suprachiasmatic nucleus'. Being an anatomical word, it is far from easy to pronounce. The word 'supra' means 'above' and 'chiasm' means 'a crossing point. This suprachiasmatic nucleus controls pretty much a vast array of behaviours including the focus while reading this article or when you want to awake or asleep. For diurnal spices like human that stay active and vigilant is because of the circadian rhythm which activates many brain and body functions. In the evening, these processes are then ratcheted down to the bottom line making us inattentive. The figure given below is one such example of your (and mine also) circadian rhythm across the day - that of your body temperature.
It represents an average core body temperature of a group of people. Starting from the extreme left (i.e 12 pm), the temperature progresses and reaches its peak in the afternoon. As the evening approaches, the path of trajectory then changes towards the bottom along with the decline in your temperature, hitting the lowest point around bedtime.
Most importantly, your temperature does not depend on whether you are awake or asleep. Even if you stay awake all night long, the body temperature would still behave somewhat similar to the above figure. We are pre-programmed with this circadian rhythm which repeats itself over and over again without any error. But one should know that the circadian pattern is not same for every individual. Everyone have a slightly different circadian timing. For example, my rhythm is different from yours. Although, there are some several rhythms that happens within us and temperature is one of the rhythms that is governed by suprachiasmatic nucleus. In short, the decline in body temperature is what that triggers sleep and it would march up and down irrespective of whether you have slept or not.
The Sleep Pressure
The twenty-four hour clock rhythm is one of the two factors that triggers sleep. Another is 'sleep pressure'. This pressure is built by a chemical called 'adenosine'. Think of this chemical as a measuring device that registers the amount of time elapsed since you wake up. The chemical continuously keeps accumulating every minute that elapses. The more you stay awake, the more the adenosine keeps accumulating and the more your brain desires to sleep. This is called 'sleep pressure'. The continous production of adenosine decreases the 'volume' of wake-promoting regions of your brain and simultaneously turn up dial of the regions that triggers sleep. As a result, you feel an irresistible urge for slumber. It happens to many people who stay awake for more than fourteen or fifteen hours a day.
In order to make themselves a little productive, some people use an artificial way of muting the sleep-signal of adenosine that makes you feel more alert and awake: caffeine. It is second most widely used and most traded commodity after oil. A psychoactive stimulant in the world and it is not a food supplement. The consumption of caffeine is one of the largest and longest unsupervised drug studies have ever found in the human race.
Caffeine successfully defeats adenosine by blocking the sleep promoting signals transmitted through receptors but it never stimulate them effectively like adenosine because it acts as a masking agent. It blocks the signal which are normally communicated to brain for few hours. The upshot: caffeine tricks your brain into feeling more alert irrespective of adenoisne level which will ultimately seduce you into sleep with time.
The levels of caffeine reaches its peak in thirty minutes after its consumption. What's more problematic is its persistence in the body. Speaking anatomically, we use a term called 'half-life' when discussing about drug's efficacy. It simply means the amount of time our body takes to remove fifty-percent of drug's concentration. And caffeine has an average life of about seven to eight hours meaning, i.e if someone takes it around 1pm, 50-percent of the concentration will be removed by 7pm. Now you are halfway there to remove caffeine entirely from your body before supper time.
~ Matthew Walker, Why We Sleep
Something about daytime naps
Now imagine that it's Sunday afternoon and you are comfortably lying on your couch, the room's temperature is at sweet spot and there's nothing on your TV worth watching. Being sedent, you eventually respond to a stimuli pointing to an opportune to catch some sleep for a while. No harm in that, right? Or maybe there is?
Napping, in general, doesn't have any side effects. Taking brief naps for a short span of time can bring many benefits, such as improved mood, reduced fatigue, increased alertness and also enhanced cognitive performance. It's the duration of your nap that determines you see positive or negative effects. The afternoon nap is typically harmless but still it could promotes health issues if it's become a long-lasting habit.
There's no doubt that naps can offer many benefits to your brain and body. Although there are many people like Leonardo Da Vinci who practiced twenty to thirty minutes 'power-naps' ritual for creativity.
As I said earlier that while we are awake during theday, we are slowly buliding up the sleep pressure and this pressures helps us to quickly crash on bed. And we release that pressure in sleep.
The Birth & Evolution of Sleep
When did 'sleep' first emerged in the history of the Earth? When did 'life' start sleeping? Maybe it emerged at the time of great apes? Or maybe earlier in reptiles or aquatic life form or in antecedents? Studying sleep across different phyla of animal kingdom from primeval to modern era might help us to find the answer. What we do know, as of now, that every animal species, without any exception, which have been studied to date sleeps or engaged with something similar to it. As a geneticist Theodosius Dobzhansky once said, "Nothing in biology makes sense except in the light evolution." But an illuminating answer to when sleep first graced the planet turned out to be far more earlier than anyone anticipated and far more profund in ramification.
But how old does it make the 'sleep'?
Let's travel back in time. Worms emerged somewhere around Cambrian explosion (at least 500 million years ago). That means it predated all vertebrate life form on Earth. This include dinosaurs likely are likely to have slept, by inference. Imagine all the triceratops and diplodocuses comfortable sitting in night for a full repose. Some other revolutionary investigation has found that very simplest unicellular life forms on Earth, such as bacteria or protozoa, that survived more than twenty-four hours exhibits active and passive phases that corresponds to the day-night cycle of Earth. A pattern that many sleep scientists believe to be a precursor of our circadian rhythm of wake and sleep.
The standard reason for why we sleep circles around a common and perhaps erraneous idea that : entering into sleep mode is necessary for us because it fix the upheaval that occurs in the brain.
The Sleep Phases
After years of countless reasearch about sleep, we found that our brain possess a sleep pattern by taking into account the two modes of sleep: NREM (non-rapid eye movement) and REM (rapid eye movement) throught out the whole night. Its a kind of cerebral war between the two which in won and lost every ninety-minutes, ruled first by NREM sleep.
REM sleeps amounts to 20%-25% percent in total sleep time in adults and almost 50% in childrens. It usually occurs ninety minutes after you fall sleep. The very first segment of REM sleep lasts about only ten minutes but it gradually get longer in later stages of sleep. The final occurence of REM sleep may persists for ninety minutes. As yu spend more and more time in REM sleep, your heartbeat and breathing quickens. This is also a stage where most of the people experience intense dreams. Most intrestingly, the percentage of REM sleep in humans keep changing throughout their lifespan and ultimately hitting the slow-waves of sleep in late adulthood.
Surprisingly, no one knows exactly why do we have REM sleep but some studies of brain shows that this stage is quite essential for keeing our sharp. Other studies also revealed that it does not only increases cognitive brain function but also decreased blood pressure and provide multitude of health benefits. A REM sleep deprevation can be detrimental to health.
NREM sleep significantly uses less energy than REM sleep. This mode of sleep is associated with brain restoring its supply of adenosine triphosphate(ATP) which is the source of energy for use and storage at cellular level. It occurs in three substages: N1, N2 and N3 or slow-wave sleep and they last about 5-15 minutes or maybe more until the NREM sleep is attained.
Stage N1 | What happens at this stage is that your eyes are closed but it is easy to wake you up, your muscles remain active, you enters in a light sleep. Your core body temperature drops and making you ready for deep sleep and it lasts about 5-10 minutes.
Stage N2 | This stage is a period of light sleep with reduced brain functions and muscle relaxations. An adult spends about 50% of their entire lifetime in this stage 2 sleep. Moving to the end of this stage, your body prepares itself to enter into deep sleep.
Stage N3 | This one assists the body to repair and regenerate tissues. Some studies says that it helps to flush out the toxic waste from brain at this stage and that slow-wave sleep gratly aids in the process. It may lasts upto 40 minutes.
As you know it's hard to catch a good night sleep in modern times but sleep should not be taken granted. So there are few techniques to achieve a good night sleep.
1. Stick to a sleep schedule.
2. Don’t exercise too late in the day
3. Avoid caffeine and nicotine
4. Avoid alcoholic drinks before bed
5. Avoid larger meals and beverages late at night
6. Avoid medicines that delay or disrupt your sleep (if possible)
7. Don’t nap after 3 pm
8. Make sure to leave time to unwind before bed
9. Take a hot bath before bed
10. Gadget-free bedroom
11. Get the right sunlight exposure
12. Don’t stay in bed if you can’t sleep
If you want to know a little more on what happens when you are sleep deprived, below is a suggested 5 minute vedio by Tech Insider.
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