Ever wonder how a concert pianist can sit down in a packed auditorium and pump out a Tchaikovsky Concerto from memory? Or how your own foot remembers just how much to press on the brakes as you turn around a corner? Or what about why it might be better to forego an extra hour of studying the night before an exam? It might just be all about how much and how well we sleep.
According to a recent study published in Nature Neuroscience, the answer to how motor memories are formed may be found by examining our sleep. According to the study, which was performed on mice, “REM sleep prunes newly formed postsynaptic dendritic spines of layer 5 pyramidal neurons in the mouse motor cortex during development and motor learning.” Let’s decode that: While mice are in REM sleep, new growth on neurons called spines—similar to tree branches or roots—are pruned. Some of the growth remains while other bits are clipped away in order to “balance the number of new spines formed over time.”
In the aforementioned study, researchers deprived a group of mice of REM sleep and compared them to a group of normal-sleeping control mice. In the control mice, some new spines (formed in neurons) were pruned, while others were fortified. However, in the sleep-deprived group, this same pruning and fortification was inhibited.
So what does this mean for humans? Basically, this research shows that by getting rid of “excessive synaptic plasticity,” REM sleep helps create more room for the acquisition and storage of new motor memories. Better yet, REM sleep helps to solidify these new spines during development and after learning. This means that if you were studying for a huge exam or learning a new activity—like salsa dancing, for example—getting a good night’s sleep may be a big help in solidifying the newly-formed information in your mind!
An article published on ars Technica UK explained that “too little REM sleep during development is known to have detrimental effects on brain maturation,” and thanks to this recent study, researchers have new insight into what the brain is really up to. “Without sufficient REM sleep during development,” they explain, “juvenile and adolescent brains may not be able to adjust the connections among their neurons to hold on to what they’ve learned.” In other words, maintaining healthy sleep patterns and getting an appropriate amount of REM sleep each night is critical to making “newly learned tasks stick.”
It has long been known that sleep heavily impacts memory. In an article posted to Harvard Health Publications, Howard LeWine, M.D. explains that “when it comes to memory, sleep is a Goldilocks issue: both too much and too little aren’t good.” He divulged findings that sleeping more than nine hours or fewer than five hours both contributed to worse performance on brain testing. In addition, an American Physiological Society article acknowledges that “over more than a century of research has established the fact that sleep benefits the retention of memory.” It’s not so much the knowledge that sleep affects memory that makes this latest study so fascinating, but that it provides us with a stronger basis for understanding how exactly the process happens and how it can benefit our daily lives.
So the next time you’re learning something new, be sure to create a quiet, dark sleep environment to help yourself catch some high-quality zzz’s. Getting your full eight hours and hitting the REM phase might just be the key to remembering all those new dance moves.
This post is part of our Sleep Month series.