If you’ve ever stayed up all night cramming for a test or taking care of a fussy newborn, you know how much the next day sucks. Now try doing that for 18 days, 21 hours, and 40 minutes straight. That is the current world record for the longest amount of time without sleeping.
And no one should be trying to break that record. For one thing, the Guiness Book of World Records removed it as a category back in 1997, so you wouldn’t even get a fun title for all of your unpleasant efforts. And for another, you could die.
But you might be surprised to hear how sleep deprivation actually kills you. Because research suggests it’s not something going on in your brain… but a whole other organ entirely. [SciShow intro] Sleep is amazing.
Who doesn’t love one extra snooze? But sleep isn’t just enjoyable, it’s beneficial for our bodies. While we sleep, our brain is doing all sorts of things.
Some we're aware of, like dreaming. But there’s also a lot going on behind the scenes. Sleep makes new neural connections, which helps us learn and store our precious memories.
It can also help our brains heal after an injury! Plus, our brains have a third shift cleanup crew, it’s called the glymphatic system and it takes out the molecular trash that our central nervous system produces over the course of the day. But it’s not just our minds that benefit.
Sleep also helps bolster our immune system, regulate hormones, build muscle, and promote healthy skin. They don’t call it beauty sleep for nothing, folks. Now, if you’re like me, you’ve experienced a bit of brain fog, an inability to concentrate, or a tendency to get distracted after a terrible night’s sleep.
So it’s no surprise that losing even a bit of sleep… let alone 18 whole sleeps… can mess with our cognitive abilities. In fact, studies have shown that a single sleepless night can impair us so much that we appear drunk. But many of us likely experience sleep deprivation in smaller, more frequent doses.
You might not pull a bunch of all-nighters, but you might have a lot of nights where you only get a few hours of sleep. And while it's easy to brush this off as the normal “rise and grind” way of life these days, this kind of long-term, chronic sleep deprivation can have serious health effects that go way beyond our brains. Poor sleep is associated with an increased risk of cardiovascular disease, obesity, mental health disorders like depression, and neurodegenerative diseases like Alzheimer's.
And chronic sleep deprivation can kill you. But what exactly causes it? Well, I certainly have no intention of volunteering for any kind of study that could find out.
And I’d wager that most other people feel the same way. So, naturally, scientists turned to animal models. The first formal studies to show the fatal effects of sleep deprivation were done back in the 1890s.
And their methods were a bit…. questionable by today’s standards of animal research ethics. And by questionable, I mean one trio of studies prevented puppies from sleeping!
And A sleeping puppy is one of the most adorable things you could ever see! Not cool, scientists! These puppies started to die within just a few days, but not before they developed some significant brain abnormalities.
To add insult to injury, these studies weren’t super useful to science, because it was impossible to tease apart whether it was the lack of sleep that caused their deaths, or the fact that the puppies were constantly being stressed out in order to be kept awake. But these studies did cement two ideas: one, that sleep deprivation can kill you, and two, that sleep deprivation primarily damages the brain. But it turns out, only one of these has stood the test of time.
It just took almost a whole century for more scientists to come along and tease apart stress and lack of sleep. In 1989, researchers at the University of Chicago turned to rats. In the team’s experiments, they paired up rats.
One rat wouldn’t be allowed to sleep, and the other was the control. The two rats were placed together on a turntable over a container of water. Any time the sleep-deprived rat dozed off, the table would spin and the rats had to move, or else be scooted into the water.
A surefire way to wake up, whichever happened. Meanwhile, the control rat could sleep whenever it wanted, so long as its partner was awake. This meant that both rats experienced an equal number of stressful events, but the control rat was able to get way more sleep.
In fact, it got about 70% of the sleep it normally would. Which I would still count as sleep deprivation, but it’s way more than what the other rat got: about 9% of its normal sleep. So the big pro of this study was that the researchers could separate out the sources of stress that produced the sleep deprivation, from the actual effects of sleep deprivation itself.
And yeah, many of their rats definitely died of sleep deprivation. But the researchers didn’t really notice any major physiological differences between the rats that could explain why. They didn’t even check their brains because none of their previous studies had shown any effect of this sleep deprivation protocol on the brain.
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And the first 500 people to click the link in the description will get a one month free trial of Skillshare. So by the end of this wave of animal experiments, a lot of sleep had been lost, but scientists weren’t much closer to figuring out how a lack of sleep can kill you. But eventually, a hot new research organism entered the scene.
You know them, and you probably don’t love them: the fruit fly. In case you didn’t know, fruit flies are the workhorses of a lot of scientific research. They’re super useful because you can grow so many of them so quickly.
They reach reproductive age in under two weeks, and can lay hundreds of eggs each time they reproduce, making it easy to have thousands of flies in a relatively short time. In your house, that’s a terrible situation. In your research lab, it’s awesome.
But that’s not all! As different as fruit flies seem from us, we actually have a lot in common, at least genetically speaking. Around 60% of human genes have a corresponding gene, called an ortholog, in fruit flies.
You can think of orthologs a bit like Microsoft Word vs. Apple Pages. The apps use different code to work on two different operating systems, but the functions are pretty similar.
And over the years, scientists have gotten really good at playing programmer and modifying these fruit fly orthologs to observe what happens, and then infer how human genes work. In this case, scientists at Harvard Medical School were able to use gene editing to keep flies awake forever. The flies in question had modifications to their neurons so they’d respond differently depending on the temperature.
If it was at least 29 degrees Celsius, some neurons that suppress sleep would stay active, meaning the flies couldn’t fall asleep. Now, for anyone thinking “I couldn’t sleep at that temperature either! ”, it’s worth noting that the temperature itself wasn't a stressor.
It’s a bit warm for what flies are normally grown at, but not drastically high. And of course, they also raised control flies at the same temperature, to show that what was killing the flies was the sleep deprivation, not the thing causing the sleep deprivation. So what happened with these sleepless flies?
Well, a s you may have guessed, they didn’t fare so well. A normal fly survives at 29 degrees for about 40 days. Without the ability to sleep, these genetically-modified dudes started dying at 10 days, and none survived past 20 days.
But if the researchers let the temperature drop below 29 degrees, and the flies were finally allowed to start sleeping on day 10, they could basically make a full recovery. That recovery took another 15 days, which is a very significant proportion of a 40-day lifespan. But it was absolutely necessary.
If the sleep deprived flies were allowed only a few days of sleep, and then were sleep deprived again, they’d quickly start dying. So something was being seriously damaged in a way that required a lot of time to recover. And that brings us back to the question of the day: if it's not the brain that causes sleep-deprived death, what organ is it?
It turns out, at least for fruit flies, it's the gut. More specifically, it's the buildup of something in the gut, called reactive oxygen species, or ROS. And as the name suggests, ROS are oxygen-containing molecules that are highly reactive.
In other words, they cause damage to other molecules, and you really don’t want them to get too carried away with that. But as scary as that might sound, it’s perfectly normal to have them inside of you. ROS are created by our body all the time, as our cells and the bits inside them do what they need to to keep us alive.
Our cells typically have a way of taking out the proverbial trash so these molecules can’t cause too much damage. But an overproduction of ROS can wreak havoc on cells, causing damage to DNA, proteins, lipids… all the important stuff. And when this research team was searching the tissues of their sleep-deprived fruit flies for biological side effects, they found a huge buildup of ROS in the gut.
Not the brain, and not the muscles, just the gut. But at this point, that finding was just correlational, so they wanted to see if the ROS was actually the cause of death. The team needed to find a way to reduce the amount of ROS while maintaining the lack of sleep.
So they turned to a class of compounds famous for their ability to tame them: antioxidants. You’ve probably heard about antioxidants as a nutrition buzzword because some research has tied them to various benefits that marketing teams can really blow out of proportion, from anti-aging to anti-cancer. But all hype aside, antioxidants do bind to and neutralize ROS to protect cells from the otherwise damaging effects that can lead to problems down the road.
And in this fruit fly study, the researchers found that a diet of certain antioxidants could restore a sleep-deprived fly’s full life span, even if it never slept again! Some of these antioxidants worked by directly binding to the ROS and neutralizing them, while others prompted the flies to produce more of their own antioxidants. Either way, a set of antioxidants worked to reduce the levels of ROS, and the flies could live to the ripe old age of 40 days… if not a teensy bit longer!
But most importantly, this demonstrated that the death from lack of sleep was not only correlated with the production of ROS, but caused by it. That said, the exact mechanism that takes us from sleep deprivation, to excess gut ROS, to death still isn’t clear. Previous studies have linked sleep deprivation and higher levels of ROS, but until now, none had connected it to death by sleep deprivation.
This means there are plenty of questions left to answer, like what’s the cause of all of these excess ROS, how do they actually lead to death, and why is ROS production linked to sleep anyways? But of course the most pressing question you might be asking yourself right now is this: Does this mean I never have to sleep again as long as I eat a ton of antioxidant rich “superfoods”? Mmmm, probably not.
After all, you’re not a fruit fly…I assume. And you’re also probably hoping to live for longer than the next 40 days. But it can’t hurt to add some berries to your breakfast the morning after an all nighter.
Just make sure you find some time to get back into a healthy sleep routine. Because you really can stay awake for the rest of your life. It’s just that the rest of your life will be a whole lot shorter than you’d like.
