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How does sleep affect your memory

Have you ever been told that the night before an important test you should sleep with the textbook under your pillow, so that in the morning you can have its contents memorised?

Turns out there is something to it. With a few minor modifications:

First, you need to make sure to actually READ the textbook before you go to bed.

Second, you don’t necessarily have to keep it under your pillow at night.

But the sleep part of this recommendation can stay. Sleep indeed does amazing things to our memory.

Sleep helps you learn

Several behavioral studies have shown that people who get enough sleep (for adults, that’s 8-9 hours a day), are able to focus and internalize new information better during the day.

There are in fact several different types of memories that our brains need to process every day. Fact-based memories are those that involve facts we need to know (like, who is the current prime minister? Or, what’s the capital of Bahrain?). Procedural memories are things we need to remember how to do (for example, how to ride a bike) and emotional memories are memories involving particular emotions like fear or excitement.

Group of children in classroom studying with woman teacher.

Three things typically need to happen to our memories: acquisition, consolidation and recall. Acquisition is when you acquire new information, or have a new experience. Recall relates to your ability to access that memory when you need it. Consolidation happens between the other two processes and is when your memories are appropriately stored, tagged and filed in your brain.

What does sleep have to do with it? Very simply, if you’re not sleep deprived, you’ll be able to focus and learn new information more effectively (acquisition) and recall it when needed. Consolidation of memories also happens while you sleep (that’s your textbook under the pillow case right here).

How does that work?

Scientists are not yet clear on how exactly our sleep does what it does to our memory, but some studies show that REM sleep (rapid eye movement sleep – that is, when we dream) is particularly important for memory consolidation.

During REM sleep, your brain “replays” experiences that happened during the day. This replay happens in the hippocampus – a brain region important for memory, and is therefore essential to the consolidation process.

Your brain also does some “pruning” of memories, deciding which ones to keep in your “important” folder (for example, the location of your new favorite coffee shop) and which ones to delete (for instance, the tweet from a random friend of a friend about what they ate for breakfast).

Think of it as your personal virtual assistant organizing your messy inbox. He needs time to do his job properly and you better not get in the way.

So, by all means go ahead and put that textbook under your pillow if you are so inclined. But make sure you sleep on it for at least 8 hour for the content to fully “sink” into your brain.

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