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The different functions of the human brain, such as sleep and memory, have intrigued scientists for decades.
Because of that reason, there is a considerable amount of research today on the relationship between memory and sleep. And while some aspects are yet to be fully understood, the existing research efforts have provided us with significant insights into how they operate with respect to each other.
Based on what we know so far, it can be said without a doubt that sleeping is definitely connected to the memory functions of the human brain. But now you may ask - how exactly do these two functions work?
Well, that is just what we have discussed in this guide. So, if you are feeling a bit curious about this topic, then jump right in!
Before we get into the topic of how sleep and memory are related, we’d like to discuss memories first. More specifically, let us delve a little bit into how we make memories in the first place.
In that context, there are three different types of memories, which are:
A declarative memory is one which consists of fact-based information. To be more precise, it helps you remember factual data, such as the capital of the US or the name of the person who invented the telephone, for instance.
On the other hand, episodic memories are the ones that help you to remember certain events that occurred in your life. Things like clearing your first job interview or the time you experienced your first kiss are all examples of episodic memories.
Lastly, there is procedural memory, which helps you remember how to do something, such as how to cook or how to drive a car. These memories are mainly instructional in nature, and they help you to learn skills that aid in your everyday activities.
In any case, there are three things that need to happen for something to become a memory, and these have been discussed briefly below.
This is the first step in making a new memory. Encoding or acquisition occurs when you come across a new piece of information or experience an event for the first time. At this phase, the memory is fleeting, which means that it can be easily forgotten. And as you can already guess, this step occurs when you are awake.
Consolidation is the second step in creating a new memory. It is the most crucial step in the process since it helps to strengthen and stabilize the memory in your brain. This event generally takes place while you are asleep.
Retrieval or recall is the step where you access a previous memory. In other words, it is the ability to remember a memory after it has been stored. Similar to the acquisition event, it mostly occurs while you are awake.
In this section, we have discussed what happens once you fall asleep. The sleep cycle is primarily divided into two different stages - rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. While sleeping, your brain cycles between these two stages throughout the night, which subsequently ensures that you get a good night’s rest. For your convenience, we have discussed each of these sleep stages briefly.
This is the stage that your brain goes through first when you fall asleep. NREM sleep is further divided into three different stages, where each stage has a distinct pattern of brainwave activity. The first is NREM stage I, which is essentially when a person transitions from wakefulness to sleep. This stage usually lasts for about one to seven minutes and is marked by a gradual reduction in brainwave activity.
NREM sleep stage II begins shortly after stage I, and this stage sees a further reduction in brain activity. Apart from that, it brings about other physiological changes, too, such as a fall in body temperature, reduction in heart rate, and relaxation of the muscles. On average, this stage lasts for about 10 to 25 minutes.
Both stage I and Stage II are collectively known as light sleep, and it is easy to wake up a person during these phases. However, once a person enters into NREM stage III or the deep sleep phase, it becomes difficult to wake them up.
During this stage, the brainwave activity slows down further and assumes a distinctive pattern which is known as the delta wave. Because of this reason, it is also known as slow-wave sleep. Typically, this stage lasts for about 20 to 40 minutes, after which a person enters the next phase - the REM stage.
Once you enter REM sleep, the brain activity picks up pace, often reaching levels that are normally observed during waking conditions. This stage is characterized by a rapid increase in eye movement as well, which is where the name comes from.
The most notable feature of REM sleep is that it is accompanied by vivid dreaming. These dreams are the result of the increased brainwave activity and eye movement observed in this stage.
Your brain enters REM sleep after around 90 minutes, and the duration of this phase varies greatly. In some cases, it can last only a few minutes, and in others, it can last for almost an hour.
Now that you have a basic understanding of memory functions and sleep cycles, it is time to address the primary question - how are these two functions connected? Well, these two brain functions share a relatively complex relationship, the specifics of which are still being studied today by scientists.
But one thing that is clear is that these processes involve the brain’s hippocampus and neocortex regions - both of which play a crucial role in learning and memory. It is thought that the hippocampus replays the entire day’s memories for the neocortex, similar to a record player. Subsequently, the neocortex processes the most important ones and keeps them stored as long-term memories in the brain.
With that being said, healthy sleep patterns have been found to be helpful for long-term memory consolidation. To put it simply, if you get a good night’s sleep, you will be more likely to remember things for a long time. This aspect can be observed for all the different memory types.
On that note, the REM and the deep sleep NREM stages play a vital role in the memory consolidation process. Based on recent research, it can be implied that slow-wave sleep helps with declarative memory consolidation. On the other hand, REM sleep helps in the consolidation of procedural and episodic memories, the latter of which is often emotional in nature.
So, the key takeaway from the above discussion is that you need to get adequate sleep to maintain proper memory function. However, this is not always possible since our modern lifestyles do not allow us to get sufficient rest in a single night. That is why memory problems are so commonplace these days, both among adults and children.
Sleep deprivation is a condition that arises when a person does not get enough sleep. A typical adult requires around seven to nine hours of sleep every night. So, if you are unable to maintain such a sleep schedule, you will become sleep deprived. And if such a situation persists for a long time, the problem will become chronic in nature.
Since it prevents you from getting enough sleep, chronic sleep deprivation affects your memory functions drastically. In such a situation, both your sleep quality and duration become poor. As a result, you will not be able to experience the full sleep cycle, which will consequently disrupt the key processes involved with memory formation.
A lack of adequate sleep impacts the neural signaling processes in the hippocampus, which is a key component for memory processing and consolidation. That, in turn, lowers the ability of your brain to remember information.
Besides, not getting sufficient rest tends to overwork the nervous system, which affects your concentration and awareness. That makes it difficult to collect and organize information, which further disrupts the memory formation process. It impacts mood and judgment as well, which is why sleep-deprived people often become cranky or tend to make poor decisions.
Sleep deprivation is undoubtedly a major problem experienced by people today, but it is not the only one. Chronic sleep deprivation is often caused due to problematic lifestyle choices, while the problems we have discussed below are more clinical in nature. And needless to say, all of them have adverse impacts on memory.
Obstructive sleep apnea is a condition where the airway becomes obstructed while sleeping. As such, the breathing pauses for a moment, which leads to several sleep interruptions throughout the night.
Because of this reason, the people suffering from this problem do not get enough restorative sleep, which causes problems in memory consolidation. Besides, it leads to excessive daytime sleepiness, which ultimately affects memory acquisition and reduces overall productivity. On top of that, current research suggests that it can cause depression too.
Narcolepsy is a neurological condition that impairs the brain’s ability to control the sleep-wake cycle effectively. A person suffering from narcolepsy will feel excessively drowsy during the daytime, even if they wake up feeling well-rested in the morning. Because of that, they will have trouble concentrating on tasks, which will affect the memory acquisition process.
Conversely, their sleep may become disrupted multiple times during the night, which will affect the process of memory consolidation. Thus, they will not be able to retain information in their long-term memory.
Insomnia is a common sleep disorder that is very similar to sleep deprivation. It is a persistent clinical condition that is characterized by the inability to fall or stay asleep. Usually, people who have insomnia wake up several hours early and can not go back to sleep, no matter how hard they try.
Because of this reason, they get little to no deep NREM sleep, which disrupts memory consolidation. It also results in significant cognitive deficits that impair their ability to perform daily activities.
As you can see from the above discussion, there is no doubt that sleep plays a crucial role in memory. And while there is little you can do about sleeping disorders apart from getting the appropriate sleep medicine, you can definitely address sleep deprivation caused by unhealthy lifestyle choices.
That is what this section is all about, for it discusses some healthy sleep tips that you can practice to sharpen your memory and improve learning. These tips have been listed below.
Believe us - pulling those so-called “all-nighters” in an effort to cram everything inside your head will do you more harm than good. If you do that, your mind will become foggy, and your motor skills will be hampered. And the worst part is that you will forget most of what you learned the night before.
Instead, if you use the tips provided above, you will notice a considerable improvement in your sleep quality, memory functions, and learning.
The increased pressure and stresses of modern lifestyles leave us with very little time to rest and relax. In fact, many people nowadays consider sleeping to be a waste of time. But in reality, it’s quite the opposite, as we have established here.
Of course, people with clinical sleep problems have little choice in this regard. The same can be said for older adults as well, who often experience memory loss as they age.
Naturally, future research in this domain will reveal more evidence about how sleep improves memory and learning. And who knows, maybe this data will be able to help the above groups of people too!