Why Do We Sleep?

Sleep. We all do it, to a degree – our bodies simply can’t go on without some. We can stay awake for days, even weeks in a row, but after a certain point, the deprivation will just trigger micro-black outs and other unsavory, uncontrollable side effects.

Yet, why do we need sleep? Do our cells require some kind of rest? Can our brain only actively function in a conscious state for so long? Has it something to do with our muscles? Our digestive system? All of the above? When one has access to all the food, water and shelter one could ask for, why is there still the need to go and sleep every single day?

Drowsiness and hunger both play two separate yet similar roles – hunger is a protective mechanism, like pain, designed to make us eat, lest we forget and starve ourselves to death. Pain, similarly, is designed to keep us from physically harming ourselves – and drowsiness is a biological mechanism to promote sleep.

When we eat, we beat hunger, by avoiding physical harm, we avoid pain (although we don’t beat it), and by sleeping, we avoid drowsiness. But again, why sleep? Well, believe it or not, but despite extensive testing and decades of research, we still don’t really know. There are, however, numerous theories, and the years of scientific evaluation have left us with a much better understanding of what sleep is and why it’s good for us.

One such theory to begin with is that sleep is a survival instinct biologically implemented to avoid the night – we’re not, after all, adapted to be nocturnal. Predators, accidents and the dangers of diminished vision can all be avoided by hibernating until the sun comes back up – at which point we wake up and get on with our lives.

This theory is somewhat thwarted by the fact that consciousness is always preferred to sleep when faced with potential danger, so it doesn’t make much sense for us to sleep simply to “skip the night”.

Another theory suggests that it’s a natural mechanism to conserve energy – naturally, food sources are not as plentiful and common to us as in modern society, and pre-historically, most of our day was spent hunting and gathering and building, until we came along the concept of agriculture. Yet nonetheless, we spent a long time being a hunter-gatherer species, and even after agriculture, many of us further north and south were forced to conserve food throughout the harsh, barren winters, while the equator-residing civilizations bore the occasional burden of droughts and seasonal shortages.

So it’s not too outlandish to suggest that when we sleep, we’re simply powering down various body functions, trying to utilize as little energy and food as possible. Our mind and automatic muscle functions continue, and we breathe, our hearts beat, our minds work – but our muscles remain largely inactive, and our body slows the production of energy to the cells. Our caloric demand drops, our body temperature takes a hit, and our metabolism decreases by as much as 10%.

A more recent explanation is that sleeping is the time our body has to repair itself from potential damage – from actual wounds to exhausted muscles and sore spots, and it also states that sleep is the time our body prefers to utilize for passive growth functions – from protein synthesis, to the application and production of growth hormone, explaining why sleep is so vital for proper growth.

Additionally, while our bodies are recovering and healing and growing, our brains are continuously hard at work – yet their work comes with a by-product: adenosine. Adenosine, additionally to being constantly produced by our neurons, promotes drowsiness and essentially creates our longing for sleep. It’s neurological effects can be blocked by certain substances, such as caffeine, but ultimately it functions as a natural hourglass – as our brain reaches its limit of adenosine, we go to sleep – and as we sleep, our body works hard to remove all traces of the substance. Then, as we wake, all drowsiness has departed and we feel refreshed and ready to go. Although this again is simply the body manipulating the brain through chemistry, it goes to show that there is some importance to sleep, seeing as we biologically go through so many measures to try and induce it.

Another recent theory dictates that sleep is most essential for brain development, and brain maintenance. The details are still fuzzy, but its undeniable that sleeping has massive effects on how our brains work and grow.

Yet in the end, whatever you think most likely, there’s no denying that sleep is important. Very, very important.

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