Sleep is Dangerous

Sleep is dangerous. Or at least with a rudimentary understanding of evolution, that’s a conclusion you could semi-logically arrive at.

Let’s journey back to our caveman days. Sleep was dangerous. Dangerous for our species. It was more dangerous than hunting woolly mammoth. It was more dangerous than climbing trees for fruit. It was more dangerous than invading a bee hive for honey.

And the reason sleep was so dangerous for our species was that if you were asleep you couldn’t care for your young. You couldn’t hunt and gather food to stay alive. And if you were asleep you couldn’t hear that hungry predator eyeing you off as a midnight snack.

And yet despite all this we still evolved to need eight hours of sleep a night! Why!?

Well, to figure this out we need to have a really basic knowledge of how evolution works – a process called natural selection.

Long long ago on a dusty African Savannah, a pre-human was born with a mutation in their hip. Let’s call this little girl Lucy. This mutation meant that Lucy’s leg stuck out at a funny angle. But it just so happens that this funny angle meant that this mutant pre-human could stand on two legs. So, instead of being the brunt of jokes from her pre-human friends, Lucy became a bit of a hero. You see, she could see over the tall grasses of the savannah to spot an approaching predator. She could move efficiently over long distances to track prey. She could carry her baby while travelling to a water hole. Lucy was a trend setter.

So what began as a mutation actually gave her a survival advantage. This advantage allowed Lucy to live longer. Living longer allowed her to have more babies… and some of these babies were born with the same mutation. In turn they lived longer. They had more babies, and over millions of years, humans evolved to walk bipedally.

So everything that we have evolved to become was the result of random mutations which turned out to help us have more children.

So at some point, sleep must have been an advantage, otherwise we wouldn’t have evolved to need sleep.

So the only way that sleep could have been selected for in our evolutionary past was if the benefits of sleep outweighed the negatives. In our environmental past, sleep was so important that the need to sleep was prioritise in our genes even if it meant we could be eaten my a sabre toothed tiger!

So sleep must be a net gain. Even with all the limitations that sleep imposes on us, it’s still more of an advantage to have eight hours of sleep a night than not to.

Sleep is dangerous. It can kill you. But it’s not as dangerous as NOT sleeping. How will NOT sleeping kill you? In just about every way you can imagine. There are a tiny few major causes of premature death or disability that aren’t protected against by getting a good night’s sleep.

Dan Williams

Dan Williams


Dan Williams is the Director of Range of Motion and leads a team of Exercise Physiologists, Sports Scientists, Physiotherapists and Coaches. He has a Bachelor of Science (Exercise and Health Science) and a Postgraduate Bachelor of Exercise Rehabilitation Science from The University of Western Australia, with minors in Biomechanics and Sport Psychology.