It is 4 am and the big test is in eight hours, followed by piano recital. You have been studying and playing for days, but you still don’t feel ready for either. So, what can you do? Well, you can drink another cup of coffee and spend the next few hours cramming and practicing, but believe it or not you might be better off closing the books, putting away the music, and going to sleep. Sleep occupies nearly a third of our lives, but many of us give surprisingly little attention and care to it. This neglect is often the result of a major misunderstanding. Sleep isn’t lost time, or just away to rest when all our important work is done. Instead, it’s a critical function, during your body balances and regulate its vital systems affecting respiration and regulating everything for circulation to growth and immune response. That’s great, but you can worry about all those things after this test, right? Well, not so fast it turns out that sleep is also crucial for your brain, with a fifth of you body’s circulatory blood being channeled to it as you drift off and what goes on in your brain while you sleep is an intensely active period of restructuring that’s crucial for how our memory work.
At first glance our ability to remember things doesn’t seem very impressive at all. 19th century psychologist Herman Ebbinghaus demonstrated that we normally forget 40% of new material within the first twenty minutes, a phenomenon known as the forgetting curve. But this loss can be prevented through memory consolidation. The process by which information is moved from our fleeting short-time memory to our more durable long-term memory. This consolidation occurs with the help of a major part of the brain, known as the Hippocampus. It’s role in long-term memory formation was demonstrated in the 1990s by Brenda Milner in her research with a patient known as H.M. after having his Hippocampus removed, H.M.’s ability to form new short-term memories was damaged, but he was able to learn physical task trough repetition. Due to removal of his Hippocampus, H.M.’s ability to form long-term memories was also damaged. What this case revealed, among other things, was that the Hippocampus was specifically involved in the consolidation for long-term declarative, memory, such us the facts and concepts you need remember to that test, rather than procedural memory, such us the finger movements you need to master for that recital.
Milner’s finding, along with work by Eric Kandel in the 90’s,have given us our current model of how this consolidation process works. Sensory data is initially transcribed and temporarily record in the neurons as short-term memory. From there it travels to the Hippocampus, which strengthens and enhances the neurons in that critical area. Thanks to the phenomenon neuron plasticity. New synaptic buds are formed, allowing new connection between neurons and strengthening the neuron network where the information will be returned as long-term memory. So, why do we remember some things not others? Well, there are fe ways to influence the extent the effectiveness of memory retention. For example, memories that are formed in times of heightened feeling, or even stress, will be better recorded due to the Hippocampus’ link with the emotion. But one of the major factors contributing to memory consolidation is, you guessed it, a good night sleep.
Sleep is composed of four stages, the deepest of which are known as slow-wave sleep and rapid eye movement. EEG machines monitoring people during this stages shown electrical impulse moving between the brain stream, Hippocampus, thalamus, and cortex, which serve as relay stations of memory formation. And the different stages of sleep have been shown to help consolidation different types of memories. During the non-REM slow-wave sleep, declarative memory is encoded into a memory store in the anterior part the Hippocampus through a continuing dialogue between the cortex and Hippocampus, it is then repeatedly reactivated, driving its gradual redistribution to long-term storage in the cortex.
REM sleep, on the other hand, with its similarity to working brain activity, is associated with the consolidation of procedural memory. So based on the studies, going to sleep three hours after memorizing your formulas and one hour after practicing your scale would be mos ideal. So hopefully you can see now that skimping on sleep not only harm your long-term health, but actually makes it less likely that you will retain all that knowledge and practice from the previous night, all of which just goes to affirm the wisdom of the phrase, “sleep on it”. When you think about all the internal restructuring and forming of new connections that occurs while you slumber, you could even say that proper sleep will have you waking up every morning with a new and improved brain, ready to face the challenges ahead.