Why Is Sleep Important?

girl sleeping on bed

“Why should I bother myself about sleep?” This was one of the questions I used to ask myself as a child, and even moreso as an adolescent. How could sleep be considered important when there were some many things to do? Study, train, hang out, etc. Important stuff! Thank heavens I’m an adult now and I have enough experience to understand the error of my ways. That, plus learning about the real effects of sleep deprivation really sobered me up. Now?there’s no question–I enjoy sleep, especially of the long and refreshing variety.


Shut up, Patrick. (Image credit: memegenerator.net)

I am now constantly amazed at the fact that I can go to bed, be unconscious for several hours, and then awaken the next day to continue life as normal. Sometimes, upon deep thought, it’s downright disconcerting! Truth be told however, very interesting things happen while we’re off in dreamland. To get a good handle on this, let’s start by understanding what sleep actually is.

What is Sleep?

Check?out this?definition from the MacMillan Dictionary for Students:

“sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles”

A little bit much to digest? No problem. All this says is that sleep has 3 major characteristics:

  • Naturally recurring loss of awareness and/or consciousness (usually daily)
  • Decreased bodily movement
  • Decreased perception of external stimuli

Some say that this is a passive state, but that would not be entirely true. While many of our internal systems do indeed exhibit lowered activity levels, the brain is actually doing quite a lot behind the scenes. As it stands, sleep actually has a cycle to its occurrence, and it is the brain that largely monitors and controls how we progress from one state to another.

Why Do We Sleep?

Despite all the research that scientists have put into studying sleep, the ultimate reasons for why we do it still remain on the dark side of the veil. This makes sleep a very mysterious phenomenon, since we can only really observe that it happens, but never really provide a rationale for why it needs to. There are several theories that seek to explain sleep, but none of them has been fully accepted. I’ve enumerated each below with short summaries of each.

Inactivity Theory

lady sleepingThe Inactivity Theory holds that we sleep really as a survival imperative that allows us to avoid being gobbled up by larger predators. Sleeping at night therefore supposedly gives us an advantage over other animals that are awake and moving around in that period, since they are most likely to be noticed…and then may subsequently become some other animal’s dinner.

I have a hard time believing this one because I don’t see a biological advantage to sleep anywhere. When you sleep, you are vulnerable (not to mention unresponsive!) so in my mind that makes you easier prey to capture. No wonder this theory isn’t very well-liked–it doesn’t quite match reality using a believable reason.

Energy Conservation

Thought to be an outgrowth of the Inactivity Theory, the Energy Conservation Theory basically says that we sleep in order to save energy. Indeed, muscular activity and body temperature both decrease so we certainly show smaller individual energy footprints during that time. But why would we need to save energy? Think about it–in the days of cavemen when food was scarce, you couldn’t really go 24×7, rest was an absolute necessity. Additionally it wouldn’t make sense to hunt at night since we’re just not built for it (maybe if cavemen had IR goggles that would have helped).

Fast-forward to today where food is much more abundant and accessible, and this theory’s relevance decreases rapidly. Coupled with the fact that the amount of energy we save during sleep really isn’t all that much–this theory is a hard sell. If we were like bears who hibernate during winter, then that would make sense, but hibernation is a very different biological process from conventional sleep as we know it.

Physical Restoration
sad man holding pillow

Tired? Get between those sheets.

This?school of thought believes that sleep takes advantage of periods of low stress and activity in order to carry out ?generalised maintenance on the body and brain. More specifically, NREM sleep is focused on bodily repair, while REM sleep seems to handle more brain repair. Ultimately, many empirical studies have shown that the body definitely uses sleep as a time to advance its own purposes: restoring tissues, overhauling cells, and supporting growth and development (for example, human growth hormone or HGH is released at no other time). The brain also flushes waste during that time which helps us feel refreshed and cognitively alert upon waking.

While this theory is very acceptable, it still has some holes–more due to our ignorance than anything else. There is a large gap in our understanding of what approximately 50% of our?sleep time actually does.?Added to that, we still do some amount of repair while being awake…so physical restoration as a reason for sleep is still under construction.

Brain Plasticity

This theory argues that sleep enhances memory and information processing capabilties in both children and adults. The purpose of this is to consolidate memories , discard unused information and to develop new neuronal pathways within the brain. Memories of places, events, and?procedures are cemented during sleep and can help enhance our cognitive performance more rapidly than in persons that are sleep deprived. It is also said that dreaming, while aiding creativity, may also be that mental space in which emotional conflicts may be resolved!

Like Physical Restoration theories, this hypothesis does not have 100% coverage of our entire sleep cycle. Though we can observe its effects in children, once moe it is difficult to explain the time spent in certain phases (eg. babies can spend anywhere between 50%-80% of their time in REM, while adults spend much less). Other members of the animal kingdom also show curious reversals, such as dolphins which exhibit increasing REM sleep as they age.

The Importance of Sleeping Well

While much of sleep remains?unknown territory, scientists have observed its impact on many aspects of our lives.?Here are 5 of the most critical ones:

moody eggs1. Mood and Emotion

Sleeping well can help to regulate your mood. Have you ever noticed yourself after being sleep deprived for any length of time? I become very irritable without good sleep, almost to the point of being a total grouch. And this is just with mild sleep loss…can you image what happens in persons who have severe sleep deprivation (such as that caused by chronic insomnia)? Rage and depression and not uncommon results in those scenarios. Exactly why this is so is unknown, but I speculate that being unsociable is the body’s way to telling us we need to be isolated so that we can sleep. It’s like the sensation of pain, the worse something gets, the more it hurts. When the matter is corrected, all is well once more. Very similarly with the sleep drive–the higher it is, the more you need to get to a place where you can safely ‘turn off’. If this means getting away from people in general, then do it! Your brain and body will both be grateful.

healing and regeneration2. Cell regeneration and Healing

Our bodies come under much stress on a daily basis, and thus we need time to rest and recover.?It has been shown that sleep can increase the rate at which cells regenerate and wounds heal, which is very important in preserving one’s health. It is also during sleep that much growth and development occurs, particularly in infants and young children.

Athletes benefit much from this as well, since sleep has been shown to improve physical performance. Do recall that strenuous exercise actually causes “microtears” in muscles. These microtears are repaired and new muscle fibers created when we sleep, so if you’re looking to build bulk, try to improve your sleep first before going after ssupplements. Remember your body carries our anabolism all on its own during sleep–that’s the process by which it builds compounds to be used for improvement, repair and regeneration.

reminder string on finger3. Long-Term Memory

Given two people studying for an exam the night before, who do you think is likely to perform better: the one that sleeps, or the one that doesn’t? The correct answer: they’ll probably both fail if they’re trying to cram! But on a more serious note, and assuming all things equal in preparation, the person that sleeps will usually outperform the one that doesn’t. This is due to the fact that poor?sleep can impact memory, oftentimes causing forgetfulness.

It’s wise to remember that memory processing and storage both occur during sleep. The actual process of stabilising a memory in one’s long-term memory is fairly complex, and involves a replay of the important information acquired throughout the day so as to determine what would be important to store. Items that aren’t necessary are?pruned, as are old memories that need not remain (hence why we naturally forget things?over time). This form of maintenance assists with our ability to recall things on a daily basis, so if you haven’t allowed it to run, you are likely to have poor information retention!

decision-making4. Decision-Making

In very much the same way that sleep deprivation influences memory, it also negatively impacts one’s ability to make decisions. Cognitive performance is known to decrease even with mild sleep loss, so it’s only natural that one’s judgment would suffer. This is one of the prime reasons why poor sleep is a major cause of injuries on the job as well as road accidents and fatalities. When we are tired, we tend to shortcut our reasoning ability which makes us unlikely to succeed at managing complex tasks. In fact, something which appears as simple as driving can take on a very different complexion to the sleep-deprived. One study showed that even moderate sleep deprivation of 17-19 hours could produce effects similar to (or worse than) having a blood alcohol concentration of 0.05%. With worsening sleep loss, this figure approaches 0.1% which is high enough to be considered drunk in many states where the generally accepted limit is 0.08%! Under those conditions, persons should most certainly not be driving or operating any form of heavy machinery.


5. Immunity
evil virus

Really wouldn’t want this guy running amok inside me…

There’s a reason why your doctor recommends plenty of “bed rest” along with your medications if you have a cold or the flu. As it turns out, good sleep promotes a well-functioning immune system, which means you’re likely to get better, faster. Getting great sleep also does more to protect you from illness which means you can be more productive on a daily basis. Note that this isn’t a straightforward relationship however…some persons with robust immune systems can pretty much go for a while without being overwhelmed. Those with weaker immune systems however can easily fall prey to colds and the flu whenever they have even minimal sleep deprivation.

There’s also a very important side to this equation–sleep allows us to manage our inflammatory response. Whenever we sleep, we tend to flush inflammatory agents (known as cytokines) from our bloodstream, which can be harmful in the long-term. Chronic diseases such as heart disease, type II diabetes, arthritis and hypertension are all linked to heightened levels of these agents. Under normal conditions, they help to protect the body, but where they are not being managed by your regular sleep maintenance cycle, they can contribute to potentially debilitating and costly conditions.

The list above is by no means exhaustive! Sleep contributes to our overall well-being in a great number of ways, so you should do all that you can to protect it. Many people may be asking themselves just how much sleep is enough? To get the low-down on that particular question, I would invite you to check on my post titled ‘How Many Hours of Sleep Do You Need?‘. Once you’ve done that, be sure to also get some tips for great sleep. Take note of everything that sleep can do for you, and be sure to include it as an essential part of your day. It’s so important to me that my Google Calendar actually has sleep as scheduled item–one which I do my best to keep.

Did you find this informative? I’d really love to hear from you regarding hat your thoughts were on this post. Drop me a line below and I’ll be sure to respond.

Sleep well until next time!



  1. Anis

    Sleeping is very important, people that have at least 8 hours of sleep, are more creative and have a better immunity, a couple of days I remember I had problems with sleeping but after doing some internet research I realised that I was doing a mistake which is exercising 2 hours before bed, I stopped doing that and the problem was fixed.
    thanks for sharing this important article with us

    1. Joshua (Post author)

      Hey Anis, I’m glad you found this informative. Exercising too close to bedtime can actually make you energised so you’d certainly have problems falling asleep. It’s good that you did your research and corrected the problem!

  2. Amanda

    Thanks so much for the helpful article! I know that I spread myself too thin, I could get much better sleep than I do but it’s so difficult to go to bed earlier. I didn’t even realize lack of sleep made such a huge impact on our immune systems. Do you know if there is any validity to himalayan crystal salt lamps and sleep aid? I keep hearing that those help.

    1. Joshua (Post author)

      Thanks for your comment Amanda. Himalayan crystal salt lamps as sleep aids…I must admit I haven’t come across that much in any of my research. I’m aware of the benefits, but have never been able to find the exact mechanism by which they improve sleep–outside of improving air quality and soothing allergies. Granted these are definitely good things because a large part of good sleep is having proper respiration. You raise an interesting question though, I’ll see if I can dig up some more information.


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