Romy asks, “Why am I so tired?”
We have no idea.
Humans have figured out where we came from, what everything’s made of, what happened billions of years ago, and will happen billions of years from now. We’ve worked out the causes of diseases and developed ways of beating them. We’ve mastered physics so well that we can fly through the air at 500 mph or talk to someone on the other side of the planet.
But we’re not sure why we spend a third of our lives paralyzed and unconscious.
Here’s one thing we do know: we definitely need sleep. If it wasn’t super important, it would be a pretty stupid idea. You can lock your door at night, but other animals are totally defenseless when they sleep — not a great move.
So why sleep? Well, if you’ve ever tried not to, you know what happens. You get a little loopy. Going 24 hours without sleep does the same thing to your brain as chugging five beers.
And if you never sleep? Scientists made some unfortunate rats stay up way past their bedtimes to see what would happen. The rats had to hang out on a disk over shallow water. If they nodded off, the disk would spin. The rat would have to wake up and walk the other way or it would get spun into the water.
Spoilers: all the rats died. But we can’t say why. They didn’t have ulcers or brain damage. All their organs were fine. As far as we can tell, they were just tired to death.
We have three guesses about why we sleep, but they’re just guesses.
One guess is that we sleep to restore whatever oomph we used up during the day. We do know that sleeping makes wounds heal faster, cancer grow slower, and your immune system work better. But we haven’t found any “life force” that drains when you’re awake.
Another guess is that we sleep to save energy. It’s true that you don’t use as many calories when you’re asleep, so you need less food overall. But wouldn’t it be easier just to eat more? And why would being low on calories make you hungry sometimes and tired other times?
The best guess is that your brain has to do some regular upkeep, and can’t do it while you’re awake. For example, your memory is better if you sleep more. Recently we found out that your brain loses unnecessary connections while you’re sleeping, so you run more efficiently. Still, though, why does that mean you have to conk out for eight hours? Your brain is great at multitasking. Right now, it’s supervising thousands of things you’re not even aware of!
To summarize, we don’t know. I’ll let William Dement, one of the world’s experts on sleep science, take it from here.
As far as I know, the only reason we need to sleep that is really, really solid is because we get sleepy.
More on this: D. T. Max, The Secrets of Sleep
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Originally published at milobeckman.com on February 4, 2015.
