How sleep helps your brain function
Lesson summary
Coming up on today’s lesson: The importance of sleep. It helps us avoid fatigue, yes, but it does so much more for our brains. Today’s lesson is inspired by a book I read this spring called, “Why We Sleep” by Matthew Walker, a British sleep scientist. It really opened my eyes—so to speak—about the importance of sleep and changed my perspective, so I wanted to share some of it with you.
What happens when we sleep
For many years, sleep had been seen as something we do for comfort. It’s something we do to make ourselves feel better. And so it is often seen as a luxury: something you do to treat yourself and therefore, something you can deny yourself. To many people, sleep something that’s not truly necessary. For example, if you really wanted to improve your career, you’d cut back on your sleep and work more. If you wanted to enjoy your 20’s, you’d stay up all night partying and go right to work in the morning. If you really loved your kids, you’d sacrifice your own sleep to spend time with them. And so on.
Sleep helps us defeat the feeling of fatigue, but it does so much more. Sleep science has shown that sleep performs a lot of critical brain functions—and people who don’t get enough sleep are missing out on critical benefits, and their performance—whether they know it or not—likely suffers.
What happens when you sleep? In short, sleep helps your brain process the information it receives. Our brains receive an unfathomable amount of information: some of it is important, much of it is not important. Your brain is hard at work sorting the important from the unimportant. Why do you remember your spouse’s birthday, but not what he or she wore 13 days ago? Because one is important, and one is not: your brain received both pieces of information and it selected the information to remember.
Sleep also helps your brain prepare to learn. When sleep-deprived, our brains are not open for business. We may hear information, but we don’t know what to do with it. As a result, we retain less in our short-term memory. A study demonstrated this clearly, taking two groups of volunteers. Both groups were asked to memorize a lot of random facts. One group got to take a nap in the afternoon, while the other group stayed awake doing menial tasks. They were tested again on different memory-related exercises later on. Here’s what happened: the group that took the nap far outperformed the group that stayed awake. The group with the nap was able to do better because their brains were cleared and ready to learn again, whereas the group that stayed awake was still taxed by the earlier activity.
If sleep prepares you to learn, then it stands to reason that it helps retain memories after you learn. And in fact that is the case. The author says it’s your brain’s way of clicking “save” on what you learn during the day. When you learn something new, memories get burned into a short-term brain memory. But your brain needs to consolidate all those memories, save the important ones, and discard the rest. The two benefits are these: first, your brain retains the important memories; second, the short-term memory is now available to receive the stimulus of the following day. This consolidation process happens during sleep. Again, tests find that subjects that sleep after learning retain a lot more of what they learned, compared to those who did not sleep.
Think back to when you had to take exams—or maybe you have to take exams now! Faced with the choice of studying for a short period of time and sleeping or staying up late and studying lots of hours, which did you choose? It’s better for your brain—and better for your learning—to get the sleep. But that’s not the choice many of us made back then.
In fact, studies show that memory retention is between 20 and 40 percent higher when you get enough sleep after learning. Forty percent is a lot! But it’s so hard to recognize in the moment that the better thing for your learning—the better thing for your mental performance—is to sleep.
Sleep is also important for forgetting. I mentioned before that your brain has to constantly decide what to keep and what to discard. We normally think of this like clearing the short-term memory. But there is another good reason to forget, and that is clear thinking. If you don’t give your brain time to process the information it has received, then you’ll cycle through lots of unimportant memories, which will distract you from doing your best.
You can probably think of a time where you were sleep-deprived, stressed out, and had a hard time making a decision. Perhaps you then got a good night’s sleep and found the problem easier to solve in the morning. This is your brain’s sorting mechanism at work. The decision is easier because your body is relaxed but also because your brain did a lot of the decision-making work while you were sleeping. Your brain made the situation clearer by processing the memories of the previous day, leaving you with only the most important information and perspectives.
Sleep science has proven that sleep is necessary for us to do our best. Tests prove over and over again that sleep-deprived people remember less and perform worse on cognitive tasks. Creativity is also enhanced by the dream activity that happens while we sleep. An irony is that people who are sleep-deprived don’t even know that they are sleep-deprived. In fact, they often deny it: they think they’re fine. They’ll tell you they don’t need sleep—and they’ll tell you proudly. But if you compare the performance of sleep deprived people with fully rested people, the group that gets the sleep always wins out.
And yet the idea that sleep is a luxury persists. In the business world, we tend to idolize people who are taking calls halfway across the world at midnight, then responding to emails at six the next morning. Offices don’t offer nap rooms. To admit you were taking a mid-day nap is asking to be fired or censured, even if it increases your performance at work.
Our employers will set certain ground rules regarding sleep, but each person has to be the one to take charge of his or her own sleep. And in Thursday’s lesson, we’ll talk about how to do that, even in the modern world we live in.
A new perspective on sleep
Two things really changed my perspective on sleep: this book and COVID. This book, because I learned so much more about what our bodies are doing while we sleep and I learned about how and why we feel differently, depending on the kind of sleep we get.
And COVID because for the first time, possibly in my life, I was getting enough sleep and consistently sleeping the same hours every day, seven nights a week. And I was stunned by how much better I felt just from the improved sleep I was getting. So that is a hint about Thursday’s lesson: it will be about what kind of sleep is best for us, and how to get the sleep we need. So make sure to tune in for that, coming up on Thursday.
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