Why Didn’t Evolution Get Rid of Sleep?

August 9, 2019

When we think of evolution, natural selection, predation, and efficiency, sleep might seem like a terrible idea. Lying dormant for six or more hours a day makes us incredibly vulnerable to danger not to mention inefficient, right?


Even though science doesn’t completely understand why we sleep at all, and being unconscious for long stretches doesn’t appear to offer any advantages, nearly every animal sleeps (even if it’s only short rest periods like insects or half of their brain like dolphins).


The longer we’re awake, the less effective, efficient, and alert we are. Our bodies need sleep. We know this, so the idea that evolution should rid us of it (as though it were tonsils or an appendix – both of which we still have) is really just an error in understanding.

In fact, the idea that evolution works to guide us toward an ideal existence that always results in progress and improves us is a misconception. Darwin’s Theory of Evolution by Natural Selection may result in evolving improved abilities to survive, but natural selection doesn’t have a design; it doesn’t tailor us to our situations or environments.

Evolution isn’t always adaptive either.

There are mutations, migrations, and genetic drifts that can cause harmful changes or disadvantages in a species. Lastly, progress, as an idea, doesn’t apply because progress doesn’t look the same for every single species.

As Berkeley University of California says, “It is tempting to see evolution as a grand progressive ladder with Homo sapiens emerging at the top. But evolution produces a tree, not a ladder — and we are just one of many twigs on the tree.”

Still think sleep is unnecessary?

With our lives as busy as they are today, filled to the brim with to-do lists, work, and obligations, we often feel like we’re missing out. Imagining life with more time might be a fun daydream. We fantasize that with more waking hours we’d be more productive, present, and prosperous, but in reality, our lives would be worse off.

First, we need sleep – there’s a reason we spend one third of lives doing it. While we’re unconscious, our bodies aren’t being lazy, they’re busily working away to restore, repair, and rejuvenate; it’s a time for energy conservation so that we’re energetic, efficient, and engaged while we’re awake.

When people and animals are sleep deprived, whether voluntarily or due to a sleep disorder, there’s a disruption in our synaptic changes, which we need for our brains to grow and change.

Even computers have a sleep function.

Think of your body as a being like an organic computer: It needs to work, but it can’t be on all the time because if it is, it’ll wear out.  

Something that is constantly “on” wastes energy and eventually breaks down. Just like computers, our bodies collect information, process, organize, catalogue, and learn but for us, those functions are performed during sleep. When we wake up, we’re not only rested, but we’re also smarter and stronger – which is a distinct advantage of sleep, evolutionarily speaking:

Not getting enough sleep or waking up feeling terrible?

If you’re having difficulty falling or staying asleep and wake up feeling worse than before you went to bed, you might be suffering from a sleep disorder like sleep apnea.

Sleep apnea symptoms include snoring, waking up gasping, night sweats, morning headaches, and daytime sleepiness. If you it, luckily, sleep apnea treatment will eliminate these symptoms and improve your quality of sleep and life. Think you might be at risk? Take our sleep quiz, or book an appointment with one of our sleep experts to find out.

Feeling Sleepy? You may be at risk for sleep apnea. Take the quiz and find out.
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