Why You Need To Sleep On It: Sleep Helps Your Brain Consolidate New Memories

At the end of every term, high school and college students find themselves staring down the barrels of final exams. Nearly every student has some study ritual to increase their chances of success on their tests.

Some students spend precious minutes, or hours, building the perfect study nest for their exam preparation. They may look for just the right desk or cubicle in the library, or carefully lay out their books and notes and brew the perfect pot of coffee, or two, or simply surround themselves with textbooks in the hopes that some of the knowledge they need to be able to demonstrate will seep into their brains by osmosis.

Some college students host their best parties just before exams, perhaps in an effort to make it easier to make an A on the grading curve. Other college students waste their time complaining to each other about how the lectures never prepare them for the test or all the questions don't come from the textbook. And some students study so hard the night before finals they fall asleep during the first question.

What Science Tells Us About Memory and Sleep

Dr. Karen Debas, a PhD neuroscientist at the University of Montreal in Canada, recently published research findings that learning a new motor task and getting a good night's sleep resulted in better retention of the new learning than learning a new motor task and not getting a good night's sleep.

Debas and her collaborators recruited 24 volunteers aged 19 to 31. None of the volunteers had ever played a musical instrument, and they were all asked to learn how to play a simple tune on a box modified to work like a piano. 

Half of the volunteers learned the tune in the morning and were asked to play it again later the same day. All of the volunteers were observed with magnetic resonance imaging (MRI) while playing the tune.

Dr. Debas and her fellow scientists observed that there were significant differences in the MRIs of the two groups of volunteers. The brains of the volunteers who had "slept on" their learning experience showed greater crosslinking and communication among the parts of the brain forming the cortico-striatal network, a group of structures in the brain that make intentional movement possible.

See Also: The 10 Most Important Signs Of Sleep Deprivation

Why Does Sleep Make a Difference in How Well We Learn?

Dr. Stephen Swinnen, a researcher with the Movement Control and Neuroplasticity Research Group in Leuven, Belgium, told Medscape Medical News that it is as if the brain practices new motor movements, in this, case, playing a simple tune on the piano, during sleep. But other researchers have found that sleep makes a difference in other kinds of learning as well.

A "Privileged Connection" In The Brain

In motor learning, Dr. Swinnen says, sleep allows the neurons that are involved in learning a new task to form a privileged connection, a kind of express pathway through the circuits of the brain, to allow the brain to use its new motor memories very soon after they are learned.

But unless your final exam is in, say, tennis, you need to be able to use a different kind of memory to make good grades. Here is what the scientific literature tells us about different kinds of memory that may relate to academic success:

• Comprehension, the ability to understand the connections between facts, isn't something that primarily occurs in your brain during sleep. It does, however, occur over time, over a period of days, weeks, months, or years. (Where you are out of college for 20 years you may find you understand facts you could only memorize when you were in school.) To really understand a subject, your brain needs time. You may be able to remember facts you learn during a cram session, but you simply have to start studying well in advance of your exam to comprehend a subject.
• It is possible to get too much sleep before a test. In one study, slow-wave sleep, the deep sleep in which the individual is "out," was linked to poorer recall on the test. Getting adequate deep sleep during the school term helps establish memories, but getting too much sleep the night before a test can interfere with how quickly the brain can recall them.
• Your brain has its own "highlighter." In the United States, college students often use colored highlighters to mark important passages in their textbooks. Highlighting the text makes it easier to through a textbook when reviewing for an exam, but the brain "highlights" information that has an emotional impact. If you got something on an earlier test wrong, for example, and you felt bad about it, your brain will emphasize those memories for your test. If you get something wrong on an earlier test and didn't really care, your brain won't care, either, and those memories will not be more readily accessible when you take the test.
• Sleep reorganizes memories. If you need to be able, for example, to recite a complicated list of facts in an exact order, "sleeping on it" without refreshing your memory before you take the test is not a good idea.

If you have limited time to study, it's best to hit the books between 6 and 8 pm, when your concentration and focus are best, and to avoid trying to study in the early afternoon, when your concentration levels are likely to be at their lowest. 

See Also: Brain Techniques To Help You Learn Better

When you finally quit studying, you need to be able to relax so your brain can consolidate all the information you've given it. And remember, even if  there is no one to tell you it's time to go to bed, getting rest--but not much more than 8 hours--is essential for test success.