While You Sleep, Your Brain Gets to Work

Discovery 1: What Is Your Brain Doing While You Sleep?

Before You Read: When you are asleep, is your brain resting too?

You go to bed. Lights out. Eyes closed. From the outside, this may look like the least productive part of your entire day. You are just lying there. Nothing to see here. Except inside your brain, the night shift has started. Sleep is not eight hours of your brain doing the same thing. Your brain moves through repeating sleep cycles, including different stages of non-REM sleep and REM sleep. Earlier in the night, you usually spend more time in deep sleep. As morning gets closer, periods of REM sleep become longer. Dreaming is common during REM. Your brain uses these different parts of the night to do some pretty important work.

Think About It: You thought sleep was mostly about resting. What is one thing you just discovered your brain is doing while you sleep?

Discovery 2: When Is Learning Actually Finished?

Before You Read: You learned something today. Is the learning finished, or does your brain still have work to do tonight?

The Night: Then Things Change, REM Sleep…

As the night continues, deep sleep becomes less dominant and periods of REM sleep usually become longer, especially toward morning. REM stands for rapid eye movement because your eyes actually move beneath your eyelids while you are asleep. REM sleep is involved in memory and emotional processing, and think about how much emotional stuff your brain collected today. Someone annoyed you. Something embarrassed you. Something went really well. Maybe nothing dramatic happened at all, but your brain still spent the day dealing with people, problems, surprises, disappointment, excitement and stress. Sleep gives your brain time to work with all of that too.

First Job: Make Today's Learning Last

Think about everything your brain dealt with today. Math. Instructions. Conversations. Something you read. A new skill in the gym. Where you left your water bottle, although apparently that last memory is sometimes considered optional. Learning something during the day is only the beginning. Your brain still needs sleep to help make that learning stronger and easier to find when you need it. As you learn, connections between brain cells begin to change. A part of your brain called the hippocampus is especially important for building new memories. But new learning is still new. Those changes are fresh and have not had much time to become strong and stable. While you sleep, your brain strengthens some of those new connections and organizes the information so it is easier to find again. Deep sleep is especially important in helping make today's learning last.

Researchers have looked at what happens when significant sleep is lost. In studies, more than 50% of new, deeper learning involving the hippocampus can be lost when sleep is seriously disrupted. That is a huge amount of learning. You can spend the day listening, studying and practising, but your brain still needs sleep afterward. Take away enough of that sleep and significant parts of the new learning you worked to build will not survive as well. Studying matters. Practising matters. Paying attention in class matters. And then sleep matters. The work is not necessarily finished when you close the book.

Put It to Work

You have a test tomorrow. You have two choices:

A. Study for another two hours and cut two hours from your sleep.

B. Stop studying earlier and protect those two hours of sleep.

Based on what you just discovered about learning and sleep, which choice gives today's learning the better chance of still being there tomorrow? Why?

Discovery 3: Why Would Your Brain Need Cleaning While You Sleep?

Before You Read: Your brain has been working all day. What happens to the waste all that work produces?

Second Job: Take Out the Garbage

Your brain has another nighttime job that sounds almost made up. Your brain cells have been working all day, and all that activity produces waste that needs to be cleared away. During sleep, fluid moves through brain tissue and helps carry away some of that waste. Scientists call this cleaning network the glymphatic system. Think of it as sweeping out and taking out the daily garbage. You would not leave every bag of garbage your house produced sitting in the kitchen forever. Your brain also needs regular cleaning and maintenance. Night after night, year after year, this is one of the ways sleep helps you maintain a healthy brain across your lifetime.

Basically, your brain has been running all day. At some point, you need to let the cleaning crew in.

Think About It: A working brain produces waste that needs clearing. Sleep helps wash some of that waste away. What do you think happens if that cleaning keeps getting interrupted night after night and year after year?

Keep interfering with that cleaning over many years and waste products may build up. Long-term poor sleep is also associated with memory problems as we get older.

Discovery 4: Why Do Little Problems Feel Bigger After a Bad Night's Sleep?

Before You Read: After a bad night's sleep, why does something small sometimes feel like a much bigger deal? Did the problem change, or did something change in you?

Third Job: Sleep and the Emotional You

There is a version of you after a good night's sleep. Your friend makes an annoying comment and you deal with it. Something goes wrong and you recover. You can concentrate. You have a little more patience. You are better able to stop and think before reacting. The problems did not magically disappear overnight. Your brain is simply better prepared to deal with them. Then there is you after losing significant sleep. Small things suddenly seem bigger. Your patience may disappear somewhere before breakfast. Someone says something that normally would not bother you much, and today it really does. Concentrating takes more effort. Frustration comes faster. You may feel irritable, emotional, stressed or simply yucky. This is not just you “being grumpy because you're tired.” Sleep supports the brain systems you use for attention and emotional regulation. Lose significant sleep for even one night and those systems do not work as well the next day. And that is a pretty lousy combination. You are dealing with school, friends, problems and stress with less attention and less emotional control available to you. At the same time, some of yesterday's new learning may not have been strengthened as well. One night matters. Your brain does not wait until poor sleep becomes a habit before it responds to the sleep you lost.

Work This One Out

Yesterday your friend sent you a message that simply said:

“Fine.”

After a good night's sleep, you barely think about it. After losing significant sleep, the exact same message really bothers you. The message did not change. So what did?

So tonight, while you are lying there apparently doing absolutely nothing, your brain will be remarkably busy. Sleep is not time taken away from your brain. It is time your brain uses for itself.

“This is the extraordinary work your brain has scheduled for tonight. Now look at what happens when something repeatedly delays the start of that work and shortens the night.”

G8 MWB-1:4