The phrase "sleep on it" is a cliche that we have all heard before—as advice received when you have a big decision ahead, or when you are stuck trying to figure out a difficult problem. The fact that this strategy works in practice is increasingly supported by scientific research. What you may not know is that this phenomenon is related to the role that sleep plays in the formation of memories.
Sleep and Memory Go Hand-In-Hand
There is more than one kind of memory. Think about it: What did you have for breakfast this morning? What's the capital of England? How do you drive a car? These questions all require you to access memories, but they are of different types. For example, you are calling something to directly mind when you remember the capital London or the toast you had for breakfast. Remembering how to drive, on the other hand, is best done using unconscious memory. Regardless of the type of memory, however, research shows that sleep is a critical component. An article in the journal Nature
states that the evidence: "leaves little doubt that offline memory reprocessing during sleep is an important component of how our memories are formed and ultimately shaped."
Memory and Disrupted Sleep
Sleep is not just one state. You have probably heard of Rapid Eye Movement, or REM, sleep, but there are many more stages to the sleep cycle. Each sleep stage has a unique set of physical, neurological, and chemical characteristics that help you with make and keep memories. Crucially, the body reaches each stage as part of a roughly 90-minute cycle that occurs throughout the night. If your sleep cycle is disrupted, by discomfort or other environmental conditions, you may never experience the sleep stages that help most with memory consolidation.
Once you have created a memory, you can retain it for days, months, or even years before recalling it. However, a study from McGill University
demonstrates that the act of recall actually degrades a memory. This research shows that once a memory is recalled, it needs to be "re-stored." In effect, you need to "re-memorize" a recalled memory in order to keep it. Quality of sleep has been shown to directly affect this re-consolidation of existing memories. In other words, a good night's sleep is critical if you want to keep enjoying the memories you have.
The term "brain plasticity" refers to the brain's ability to change its structure in response to new experiences. This means that a healthy brain is able to reorganize itself. On the other hand, a brain without plasticity is going to keep on making the same mistakes over and over again. A study published in the Annual Review of Psychology
put test subjects in an fMRI—monitoring the brain while someone is performing an activity—before and after a night of sleep. These brain scans showed new activity in control structures—providing evidence that brain plasticity correlates to sleep.
Developing Motor Skills
Did you know that even physical memory is enhanced while you sleep? A study at Harvard Medical School
showed that people who experienced deep, slow-wave sleep experienced overnight improvements in motor skills learned the day before. On the other hand, subjects who received training in the morning and were evaluated 12 hours later in the day, without sleep, experienced no such benefits. In fact, this study showed that a night of high-quality sleep produced more than double the improvement of an additional skill training session. Perhaps we need to change the saying from "practice makes perfect" to "sleep makes perfect."
You Are How You Sleep
As the science demonstrates, your ability to form and retain memories is deeply connected to the quality of your sleep. If you want the healthiest and most undisturbed night of sleep possible, you need to pay attention to what you're sleeping on. Make sure that you are surrounded by only the highest grade, most natural materials. Not only is it the smart choice, but it is the choice that will make you smarter.