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Carlos Del Rio-Bermudez
Carlos is a neuroscientist and a medical & science writer with more than eight years of research experience in the field of Neuroscience. Prior to working full time as a medical writer, he was a postdoctoral researcher at the University Hospital of Bern (Switzerland). Carlos obtained his PhD from the University of Iowa (USA), supported by the Fulbright Program.
Some of the areas Carlos focuses on are RNA therapeutics, Rare Diseases, and REMS/RMPs. He has authored multiple original research papers in top journals in the field, book chapters, and periodicals. Carlos has also participated in international scientific meetings; most notably, he was invited to present his dissertation research at the 2018 Gordon Research Conference on Sleep Regulation and Function.
Do you still think that your brain “shuts down” when you sleep? Contrary to popular belief, scientists have revealed over the past decades that sleep plays a very active role in a variety of physiological processes and supports important cognitive skills such as learning and memory. And that role is even more important than we thought!
A 2013 review looking into the association between sleep, memory, and brain plasticity highlighted how essential sleep is in the process of learning. Indeed, it seems that a lot of the biological processes that are required for learning and remembering new stuff happen during sleep. It also seems to be clear that sleep deprivation severely impacts our memory.
So, why does sleep affect learning so much? And what’s the science behind it?
Watch this video to learn how your memory works, and how you can become a more efficient learner by prioritizing your sleep.
How Do We Learn Things?
The learning process can be divided into three parts:
- Acquisition refers to the introduction of new information into the brain.
- Consolidation is a process of embedding new information into our memory. Once a memory is consolidated, it becomes relatively stable.
- Recall refers to our ability to access and retrieve that information, consciously, or unconsciously.
And while acquisition and recall mostly happen during waking hours, consolidation heavily relies on a good night’s sleep. Interestingly, although we thought the acquisition of new memories wasn’t possible during sleep, recent studies suggest that this may not be true after all.
Different Types of Memory Included in Learning
To understand how new information gets embedded in our brains, we first need to understand that not all information is the same. How we process data depends on the context and our emotional state. And based on this, different parts of our central nervous system (CNS) get involved.
While our central nervous system is incredibly complex, we can say that the neocortex, cerebellum, hippocampus, and amygdala are key structures involved in learning and storing different types of newly acquired information.
Memory can be classified into the following types based on the level of awareness required to learn and access the acquired information. In addition, these forms of memory seem to rely on different brain systems:
1. Declarative memory (or “knowing what”) is our ability to learn and recall facts, and it can be further classified into episodic memory and semantic memory. Episodic memory refers to autobiography events and their context (who, what, when, where). For instance, remembering all the details about your wedding would be a good example of this type of memory. On the other hand, semantic memory deals with general knowledge and facts that do not depend on a specific context. These include facts, ideas, or concepts. A good example is remembering the capitals of different states.
2. Procedural memories (or “knowing how”), also called nondeclarative memories, are all the little things you do without even noticing, like riding a bike, signing a document, or tying shoelaces. These can be obtained and recalled without conscious effort. However, the learning process is slower and requires repetition.
How Does Memory Consolidation Happen During Sleep?
Our ability to retrieve information we just learned is highly dependent on adequate rest. A study looked into the link between sleep and the ability to recall newly acquired knowledge. Two groups of students were taught a series of paired words and were then tested on them 12 hours later. The “no- sleep” group learned new information in the morning and then had to recall it 12 hours later, with no intervening sleep or naps. Participants in the “sleep” group were taught in the evening and were tested the following morning after a night of sleep.
And the results were amazing. Even though participants in both groups spent the same amount of time learning new information, students who had a chance to doze off before the test showed an increase of approximately 20% in the ability to recall what they’ve learned as compared with the no-sleep group.
The opposite is true, as well. A 2013 study showed that students who experienced sleep deprivation showed impaired ability to recall what they have learned.
We go through different sleep stages every night, and they are all critical in the process of learning. So, let’s go over how our sleep architecture looks, and how each part helps us learn.
NREM Sleep and Learning
NREM sleep consists of several stages. We experience light sleep in the initial stages of a sleep cycle, and it accounts for 50% to 60% of total sleep time. It is typically followed by a phase of deep restorative sleep which ends the NREM part of the cycle; then, REM occurs.
Light sleep plays a massive role in the consolidation of declarative memories.
To this end, scientists have proposed several models of how sleep impacts learning; one of them is the so-called the reactivation hypothesis. This mechanism suggests that our nightly rest is a perfect time to strengthen certain memory traces. Our brain can do that by selectively activating neurons involved in different memory circuits. Many scientists believe that the electrophysiological signatures of NREM sleep called sleep spindles are essential for the whole process, with a lot of studies, like this one from 2018, supporting the claim. Researchers believe that sleep spindles support communication between key brain areas involved in the consolidation of memories. Specifically, they represent a transfer of information from the hippocampus where memories are stored temporarily, to the neocortex where they go in long-term storage.
A 2018 study investigated the link between sleep, learning, and improvement of problem-solving skills. Children who spent more time in stage 2 of light sleep sowed a great performance improvement. Sleep spindles also correlated with performance, highlighting their importance in learning.
Since light sleep shows positive effects on the consolidation of declarative memories, napping seems like a natural boost to help you learn.
A new study published in the Sleep journal was aimed to test this hypothesis. Participants had to learn detailed factual information and were tested 30 min and 1 week after learning. In between learning sessions, some participants were allowed to nap, others watched a movie, and the rest were asked to cram for the test.
Both cramming and napping improved memory recall as compared with watching a movie when participants were tested 30 min after the last study session. Strikingly, when scientists then retested participants after a week, only napping maintained these benefits, while cramming did not. These results indicate the clear benefits of napping on memory retention, and it looks that the effects are long-lasting.
Deep sleep is the third stage of the sleep cycle, and it is the time when our brain repairs itself, so to speak. People who don’t get enough deep sleep feel fatigued and can experience brain fog. Also, deep sleep is vital for memory consolidation and for restoring the brain’s ability to learn efficiently.
REM Sleep and Learning
Rapid-eye-movement (REM) sleep has mostly been linked with nondeclarative, procedural memory.
However, some other studies show that the REM phase that follows slow-wave sleep plays a significant role in the consolidation of integrative memories such as learning the vocabulary of a new language. The authors suggested that REM sleep is responsible for integrating recently discovered information into already existing memory networks, which is essential to learn new complex concepts.
Research also finds REM sleep to be essential for processing emotional memories as REM sleep duration, and density are increased after stressful daytime events. Additionally, this sleep stage appears to affect how we react to future emotional stimuli. For instance, people lacking sleep and REM, in particular, are more sensitive to these events.
We know now that sleep affects learning and memory, but is the opposite true? can learning change our sleep architecture?
A study published in the Journal of Cognitive Neuroscience looked into the effects of the pursuit rotor task on sleep phenomena and architecture. The pursuit rotor task is a way to test hand-eye coordination by asking the participant to follow a moving object with a cursor. It tests visual and motor abilities and helps measure procedural memory. Interestingly, the learning-dependent changes in sleep microarchitecture were dependent on the initial skill levels of the participant. High-skilled participants experienced higher sleep spindle density in stage 2 of light sleep following the learning of the motor task, while low-skilled individuals showed greater REM sleep density.
This is an excellent example of how complicated the relationship between sleep, memory, and learning really is.
And while scientists are still trying to figure out all the mechanisms connecting sleep and learning, what we do know is that proper night rest is essential for cognitive performance.
The saying goes that you can’t teach an old dog new tricks, but we say let the dog sleep, and you just might!
You should make a night of sleep your priority, and you’ll see all the benefits on your cognition, health, performance, and overall well-being.
If you are struggling with getting enough sleep regularly, check some of our videos where we bring you the best science-based sleep tips that help you become a better sleeper. If your sleep problems become chronic, you should consult with your doctor, and they may refer you to a sleep specialist.
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Dusan is a biologist, a science enthusiast and a huge nature lover. He loves to keep up to date with all the new research and write accurate science-based articles. When he’s not writing or reading, you can find him in the kitchen, trying out new delicious recipes; out in the wild, enjoying the nature or sleeping in his bed.