When our head hits the pillow at night, we are open to the possibility of dreaming. But this isn’t the only activity occurring while we slumber. At night, studies have shown that sleep can improve memory and learning. Strange but true. While you sleep, there is an opportunity to remember to take out the garbage in the morning, and/or learn how to play the chorus from James Taylor’s “You’ve Got a Friend.” So obviously the burning question is the following: How does sleep help memory and learning?
Memory and Learning
Surprising or not, we will spend close to 30 percent of our life sound asleep with our eyes closed. Granted, it is time spent repairing our cells and restoring energy to our souls. But still, it seems like there should be some way in which we can tap into and maximize this time. As we sleep, the brain has a unique approach to memory and learning, which differs to what occurs during the day. But it is all interrelated. Throughout the day, our brain gathers information and at night, this self-same information is sorted and stored. Saving what we have learned for a rainy day so to speak. Nevertheless, we do not need all of this daily information so sleep allows our brain to keep what is relevant, and what isn’t disappears from our memory banks. The end result is a connection that is made between information learned during the day and our memory.
According to recent research, memory with regard to sleep is more about allowing your brain to rest certain areas so that daytime memory can improve. Sleep memory is not necessarily the ability to form or remember while we slumber. It is all about consolidating memory as a study published in the World Journal of Biological Psychiatry demonstrated. A phenomenon known as ‘sharp wave ripples’ assists the brain in merging memories while we sleep. During slow wave sleep, sharp wave ripples replay information within the hippocampus of the brain. Synchronized to occur at the same time are slow oscillations that transfer memories into long-term storage in a different area of the brain known as the neocortex. In a nutshell, the brain moves old memories out to make way for new memories during daylight hours.
And now we need to make the leap between memory and learning. Despite the fact that we are not conscious when we sleep, our brains can still grasp information—especially sensory information. In the past, studies looked at a possible relationship between our sense of smell and memory. However recent research conducted by a group at NYU Langone Medical Center and published in Science demonstrated that there is a connection between smell and memory while a person sleeps. If there was an association with an odor when they awoke from sleeping, study participants were able to recall a past memory.
A group of researchers in Israel decided to take their study a step further. Their experiment paired a tone with a scent and discovered that the sleeping participants were able to be conditioned to have the same response to the tone as they did to the smell. They concluded that our brains while asleep can process sensory stimuli, such as an odor, in the same way that we can while we are awake.
How exactly is this possible? After one falls asleep, learning occurs because the brain is stimulated to grow the tiny protrusions in the brain known as dendritic spindles. In turn, these spindles then connect to other parts of the brain, which enables the information to be passed along.
It is one thing to make a connection between a smell and a memory and another to make one between words and the sound they make, and understand it all. Thus moving away from smell and memory studies, researchers instead decided to look into sounds and comprehension. Northwestern University investigators had a theory that a short tune could be learned by study subjects during sleep. They had a theory worth testing. If a 12-note tune was played during said sleep, the sequence could be taught. The results of their study were shared in Nature Neuroscience. They found that study participants had a 4 percent increase in the recall of the tune over than those who did not hear the tune when they slept. According to Paul Reber, co-author of the study, what the results boil down to is that if learning while sleeping is connected to a specific sound, then the information will be remembered.
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