Chapter 5

Sleep, Exercise, and Human Memory — The Relationship (Improving Your Memory Part III)

Sleep and Exercise are tonics for our minds!

When talking about improving the memory, not many people think of exercise, let alone sleep. Not many people know that they can actually improve their memory by exercising and sleeping more.

When college students are preparing for examinations, sleep and exercise are usually one of the hardest-hit actions. Many people have been made to believe that you need to sleep less to learn more. But what if the reverse is true? What if you need to sleep more to learn more. What if you need to exercise more to learn more.

Sleep and exercise are so connected to our brain that we need a whole chapter to explain the relationship. In this chapter, we are going to be looking at ways sleep and exercise affect our memory and how you can use these two actions to better your memory.

Sleep and Memory: A Simplified Guide to the Complex Relationship Between the Duo

If there is one thing we all have in common as human beings, it is our natural disposition to sleep at certain times, with quantity differing from one individual to another. One other thing all living human beings have in common is the memory; likewise, with its power differing from one individual to another.

There are two keywords in the title of this section: “Simplified” and “Complex”; a rather paradoxical combination, but a clear one. In fact, if we have not been backed by mountains of research before embarking on writing this section, it would have turned into a conundrum for us too.

You see, what lies behind sleeping is far more than what meets the eye, and if you have read other chapters in this guide, you would know by now that what lies behind the human memory also goes just beyond remembering and memorizing things.

Put under scientific scrutiny; sleep becomes a very complex subject for any investigator. When subjected to rigorous scientific investigations, what lies behind human memory can likewise depress any investigator with its complexity level.

Thus, this section is about to tackle two phenomena that are – in the light of science – very complex in their own rights, while equally sharing a complex relationship.

So those two keywords in the title of this section are important and deliberate because we want to simplify this complexity wherever they are found.

And where are they found? They are found in the popular complaints of people who are suspecting a relationship between their sleep and their memory – for better or for worse.

They are also found in the publications of doctors, scientists, sleep specialists, and memory specialists that have been written to confirm or repudiate their suspicions.

Note that even with ongoing scientific investigations and constant yield of new information, our research suggests the relationship between sleep and memory will most likely remain complex for a long time.

Our attempt is just to educate you by classifying and presenting the available knowledge about them in an organized, easily digestible, and orderly manner. And of course, in a uniquely Infovore Secrets style!

So, let’s do that!

Why Do We Have to Sleep?

We have to sleep because sleep allows the body and the brain to rest. Rest is necessary for the recovery of stressed body systems. Our daily life activities are often responsible for overstressing our body systems, so we need that rest to recover.

More importantly, it is fairly a common piece of advice to get a good sleep every day. This advice was borne out of the common realization that a good sleep almost always results in a refreshed body and mind, and this is particularly helpful for people who need to use their mind and body rigorously every day.

In fact, on the average, most people would spend at least 25% of their lives sleeping.

We all need varying amounts of sleep, depending on lifestyle, health, and age. For college-aged populations, research has suggested a sleep time of 7-9 hours per night. ^[1]

In fact, there is a reasonable evidence to suggest that lack of sleep might make the ability to learn new things drop by up to 40%! ^[2]

Lack of sleep can affect a part of the brain known as the hippocampus, which is important for the making of new memories.

The Sleep Crisis

Despite the benefits of sleep mentioned in the preceding paragraphs, there is a sleep crisis currently going on.

Many recent statistics and researches are pointing to a worrying reality: people are not sleeping enough. People are not getting enough sleep to maintain optimal body and brain health.

It is even more worrisome because it is fairly more common among college-aged youths who are at the prime of their lives; people in age groups with a lot of potentials to have superb body health and brain vitality!

For example, according to the American Sleep Association, 50 to 70 million US adults have a sleep disorder. They further stated that 37.9% of people reported unintentionally falling asleep during the day at least once in the preceding month^[3].

Also, in an article published on the Center For Disease Control and Prevention (CDC) website, it was noted that more than a third of American adults are not getting enough sleep on a regular basis^[4].

The two resources cited above point to a sleep crisis.

This crisis — apart from the obvious immediate disadvantages it presents to work and schooling —  will also have severe consequences for human health in the long term, especially the human brain health, of which the memory is a principal constituent.

Let’s gradually elaborate on how this will happen.

When we are sleep-deprived, our attention, especially vigilance, is affected,^[5] making it more difficult for us to learn, act, and form memories.

In addition, a prolonged lack of sleep has been associated with diseases like diabetes, depression, high blood pressure, and mental distress.^[6]

The Warning Bells

For decades, doctors, scientists, researchers, sleep specialists, and memory specialists have been sounding a note of warning to the public through various publications – formal or informal. These warnings were borne out of the increasing knowledge that was coming to light about the relationship between sleep and memory.

These relationships are not always clear, not always positive, and not always conclusive, but there is a strong, tough connection nonetheless.

Many research works have proven that there is a positive relationship between adequate sleep and a good memory, and equally that a negative effect on the state of the human mind and memory occurs when there is a lack of sleep.

Though these research works and warnings/opinions have proven their points using various approaches, methodologies, and investigation subjects, they have all arrived at almost the same answer. The answer is that there is a strong relationship between sleep and memory. This relationship can be positive or negative, depending on the variables.

Let’s briefly examine a number of research works that have established a relationship between sleep and human memory.

1. In a 2005 study published by Rauchs G. et al. on the relationships between memory systems and sleep stages, they stated that “several lines of evidence support the hypothesis that sleep is involved in the off-line reprocessing of recently-acquired memories.” ^[7]

In the same study, Rauchs G, et al. noted that the “four long-term memory systems (procedural memory, perceptual representation system, semantic and episodic memory…)” benefit from sleep.

2. In a study conducted by researchers at Georgia Institute of Technology, participants were asked to participate in a memory test involving electroencephalography (EEG) to measure brain wave activity.

The study discovered that “maintaining good sleep quality is especially important for memory performance in older adulthood.” ^[8]

3. In a study published by Boyce R. et al. (2017), the abstract of this study was quick to sum up their findings: it says that by their use of “electrophysiological recording and optogenetic techniques,” they have been able to demonstrate “for the first time that neural activity occurring specifically during REM sleep is required for spatial and contextual memory consolidation.”^[9]

4. Hershner and Chervin (2014) noted in their research work that sleep deprivation and daytime sleepiness among college students can result in an increased risk of academic failure, compromised learning, an increased risk of accidents, among others. ^[10]

5. According to a research work done by Nicola Celllini et al. (2016), it was noted that a daytime nap aids the consolidation of declarative memories presented before and after sleep^[11]

6. Using mice, a four-year-long study was able to demonstrate the physical proof of increased and decreased synapse activity in mice brains. Researchers found that brain neuron synapses shrink (by about 18 percent) during sleep to allow for more learning.^[12] Although this research was done using mice, a similar process is expected in human beings.

7. In a study by Drs. Bryce Mander, Joseph R. Winer, and Mathew Walker (2017) at the University of California on the relationship between sleep and human aging; they opined indirectly or directly that sleep plays a crucial role in memory decline usually observed as we age.^[13]

8. Dr. Robert Stickgold of Harvard Medical School is a famous sleep expert. During a session with News In Health (NIH) to explain the relationship between sleep and memory, Dr. Stickgold opined that sleep seems to be “a privileged time when the brain goes back through recent memories and decides both what to keep and what not to keep” ^[2].

Relationship Between Sleep and The Memory in Brief

Let’s simplify this complex relationship even further. From the many popular studies we have quoted above, we have learned that:

a. Sleeping before or after learning is important in forming and consolidating memories.

b. Sleep seems to help in making relevant connections between pieces of information we learned before sleeping. This is probably why whenever we “sleep over” a problem, we usually quickly discover a good way of solving it after waking up.

Experts have stated that memory/learning involves three distinct stages: acquisition/encoding (of information), consolidation/storage (of what is learned in the memory), and recall/retrieval (of what is learned from the memory). Please see Chapter 1 of this guide to learn more about these stages.

All the three stages must occur before successful learning can be declared. However, several studies like those we quoted above have shown that a reduction in total sleep time or specific sleep stages can impede a person’s ability to encode, consolidate, or recall new information.

Sleep Apnea and Memory Loss

Sleep apnea is a kind of sleep disorder, and it has been identified as a potential cause of memory loss. This chapter won’t be complete without discussing it.

Sleep apnea is a breathing disorder characterized by pauses in a person’s breathing while sleeping. The more common type of sleep apnea, called “obstructive sleep apnea’ is caused by the relaxation of the throat muscle too much during sleep to allow normal breathing. The relaxation of the muscles of the throat constricts the passageway for air. This often makes sufferers gasp for air regularly and repeatedly suddenly while sleeping. Sufferers also often snore.

People with sleep apnea may report mental problems such as poor concentration, difficulty with memory, depression, among others.^[14]

In fact, a report from the University of California, Los Angeles, noted that obstructive sleep apnea might damage the brain in a way that can affect memory, mood, and cardiovascular system.^[15] The same report found out that patients with untreated sleep apnea have significant permeability in the blood-brain barrier than healthy people.

In another study, after analyzing data from 14 studies involving more than 4.2 million adults, researchers were able to show that people with sleep apnea are 26% more likely than people without the condition to experience cognitive decline. ^[16]

Although it is important to note that a study like this does not unilaterally prove that sleep-disordered breathing (i.e., sleep apnea) causes cognitive decline, it provides evidence that it might “worsen the problem or hasten its onset” ^[16]

If you experience a milder form of sleep apnea, lifestyle changes like quitting smoking (if you smoke) or losing weight (if you are obese or overweight) might help. You might also avoid anything that can trigger an allergic reaction if you have nasal allergies.

On the other hand, if your sleep apnea is more serious or you don’t get any improvement after trying the suggestions above, please see a qualified medical practitioner.

So How Many Hours of Sleep Do You Need?

Sleep is a fundamental part of human life, but the amount of sleep we need varies from one individual to another.

Sleep recommendation varies across age groups,^[17] and some people even perform excellently without following this recommendation.

Sleep recommendation is just a general recommendation, and many people will benefit more if they can get a custom recommendation. In fact, too much or little sleep can affect your memory^[18]. Having a nap in the afternoon may also benefit your memory ^[19].

That said, it will be difficult to give the exact number of hours of sleep you need (as an individual) to increase your brainpower. However, if you are an adult, working toward seven hours of sleep per day may bring some benefits. Taking afternoon naps might also help.

Recommendations to Help You if You Have Problem Sleeping

The aim of every individual is to keep the memory sharp, reliable, and working. If sleep deprivation has been proven so far to be a factor in memory loss, then – logically – having an adequate sleep will be the solution to the problem. It’s an open secret that many of us are simply unable to get adequate sleep, majorly due to our lifestyle choices.

To proffer some solutions, let’s examine some ways you can get adequate sleep:

1. Always go to bed when you feel drowsy. Ignore the temptation of the TV, late-night internet surfing or book reading to interfere with your body’s natural call for sleep.

2. Avoid watching TV in bed. Avoid using your digital devices in bed too, because of their blue backlight. Among other health problems it may cause, blue light has been accused of interfering with the ability to fall asleep.^[20][21] If you must use your electronic device at night, consider wearing blue-blocking glasses.^[21]

3. Avoid taking caffeinated products close to your bedtime. This includes coffee and energy drinks.

4. Make sure your room is at a conducive temperature for sleep.

5. Clear your sleeping area of a potential source of sleep disruption: clear your bed of clutter, close the shutters, and turn off the radio. You might also consider turning off flashing accent lights.

6. Get sleep/eye masks or earplugs if visual or auditory disruptions are the reason why you can’t sleep.

7. Create a regular bedtime for yourself and be punctual. You have to be disciplined with this.

8. Avoid food that may interfere with your sleep. For example, if you are lactose-intolerant, avoid food like milk, cheese, ice cream for dinner.

If there was ever a complex relationship between sleep and memory, we hope through the sections above, we have made it simple.

Exercise and Memory: Muscling Your Way to a Better Memory and Mental Health

In the previous section, we talked about sleep as a necessary ingredient for a better memory. It is now time we discuss its twin sister – exercise.

We are sure you already know a lot of things about exercise. Information about the benefit of exercise on human health are a dime a dozen – it’s in our subscription magazines, it’s on the news, it’s on the internet, and it is even on TV programs and shows.

Even if you have never engaged in any formalized exercise routine before in your life, you already know (and accept), for example, that exercise burns fat in your body, helps deal with cholesterol, prevents you from getting obese, and might help you build muscles.

Obviously, this section is not about disproving all the facts mentioned above! But let’s ask you, have you been able to see more to exercise beyond these? We guess no.

All over the world, people rightfully have optimistic beliefs about exercise. While not all of these beliefs are correct, most actually are, and they are derived from accurate observations made by people involved in fitness activities and even from people that are not into fitness.

Many will easily testify that they feel a sense of reinvigoration and re-newness after a bout of vigorous exercise. Ironically, many will even swear that, of all things, their tonic for fatigue is exercise!

Actually, most of them are right. Scientists, especially psychologists, have agreed with many of their observations from a scientific point of view. They have also praised the mood-elevating quality of exercise in different papers, interviews, and publications. But for the small number of people who have claimed that bouts of exercise not only make them more refreshed but also lessen their depression, they just don’t know how right they are.

The Link Between Exercise and Mental Health

Evidence showing a link between physical exercise and better mental health is growing. In fact, it is growing so fast that it is now almost impossible to ignore.

Many research works have affirmed the positive benefits of physical exercise on various aspects of mental health, from stress relief and mood improvement to memory and cognition improvement.

Indeed, research work has now shown that exercise, if met by some certain preconditions, can be as powerful in treating mood disorders like depression as the use of antidepressants. ^[22]

For scientists, making a far-reaching proclamation like this has taken a long time in coming. In the form of field trials, participant observations (in studies), and interviews, researchers have been looking at possible links that might exist between exercise and memory for a long time.

The accumulation of data from all these varying sources is now quite sufficient to confidently confirm such a link.

However, scientists still need to know with more certainty how much exercise is needed to achieve certain levels of mental improvement in different individuals and if exercise can be combined with other therapies.

In addition, we need to understand the link between the brain and exercise better. Although we have learned quite much, what we don’t know yet is probably far more than what we already know.

Exercise and Human Brain – What Research Works Tell Us

Exercise itself is an activity that tasks both the body and the mind. It involves rigorous muscle use, yet often requires concentration, attention, and proper coordination of the body with the mind to make it successful. This is probably where it starts leaving an effect on the brain.

Let’s examine a number of ways exercise is helping our mental health.

1. Exercise and Stress

Stress and how the body responds to it is a big factor in mental health. Indeed, some experts believe exercise can be a way to teach the brain how to deal with stress.

In a study conducted by Emma and Harriet (2014), a modest support was found for the claims that regular exercise protects against the negative emotional consequences of stress. The study also suggests that exercise has beneficial effects on healthy individuals. They, however, admitted some limitations in the study and suggested that future studies are needed^[23].

2. Exercise and Reading

Do you know that you can recall more if you exercise immediately after reading?

In an experiment done by Steven B. Most et al. (2017), it was found that women who perform 5 minutes of low-impact exercise immediately after learning were able to recall information better than women who did not involve in exercise.^[24]

This research suggests that there is a possibility to retain information better if you follow a study session with a light form of exercise like walking, especially if you are a woman.

3. Exercise and Long-term Memory

In a research work done by Emily, Eveleen and Paul (2017), it was found that high-intensity exercise prior to memory encoding (i.e., prior to the acquisition of a piece of information) was good for long-term memory. ^[25]

Additionally, exercise has been found to benefit cognition and memory more in elderly human beings.^[26] Physically active elderly persons have been found to perform better in memory and reasoning tasks than those that are not.

We have written an exhaustive article on Alzheimer’s disease (a neurodegenerative disease of the elderly), and how exercising can help reduce the risk factor for developing this disease in the elderly. You can read the article here.

There is also a piece of evidence that shows that introduction of exercise into the routine of people can increase their anterior hippocampus size. In a research work done by Erickson et al. (2011), it was found that aerobic exercise training in 120 older adults produced an increase in the size of the anterior hippocampus, leading to improvement in spatial memory^[27]. The research found that exercise training increased the hippocampal volume by 2%. While 2% might not sound much, this might add up to an appreciable improvement if the exercise is combined with other therapies.

Spatial memory, as the name implies, is the form of explicit memory that we use when trying to navigate a familiar place.

Furthermore, explicit memory (also known as declarative memory in some quarters) is the form of memory that emanates from consciousness. Explicit memory requires conscious effort from an individual to come into play. Explicit memory is one of the two main forms of long-term memory. The other being implicit memory.

4. Exercise and Depression

Although there are several more definite approach to treating depression, some recent reviews of studies investigating the effects of exercise on mental health have suggested that exercise could be a valuable addition to treatment plans for clinically depressed patients.

For example, in a literature review done by Lynette and Frank (2004), based on data available to them, they opined that the addition of exercise could improve treatment outcomes for many clinically depressed patients^[28].

5. Exercise and Anxiety

Research has suggested that exercise can be used in the management of anxiety. In the literature review done by Elizabeth et al. (2018), after studying many research works, they concluded that “exercise programmes are a viable treatment option for the treatment of anxiety” ^[29]

In another literature review done by Gregory et al. (2015), they also concluded that exercise might be a useful treatment for anxiety. However, they noted the paucity of data from well-designed randomized clinical trials and hence the need for further research on the subject.^[30]

6. Exercise and Mild Cognitive Disorders

Studies have linked a better mental functioning with participation in aerobic exercises in older adults who have a mild cognitive disorder.

In a particularly interesting study, 160 older adults with mild cognitive impairment who live a sedentary lifestyle are assigned differing tasks.

Their tasks were any one of these: do vigorous daily aerobic exercises; or eat a diet that prevents hypertension; or combine the exercise with the diet; or do none of these, and instead receive a health education.

At the end of the six months study, it was observed that those who either exercise alone or who combined the exercise with the diet performed best on memory-related tasks.^[31]

7. Exercise and Creativity

In an experiment conducted by Hannah et al. (1997), exercise was shown to play a significant role in increasing creativity.^[32]

There is also evidence suggesting that a more outdoor life is good for creativity. You can read more about this in our article about the benefit of spending time in nature on memory and mental health.

8. Exercise and Working Memory

Exercise has also been found to be beneficial to working memory. Please note that short-term memory is part of working memory.

Moriya et al. (2016), found that physical exercise benefits the prefrontal cortex activity and enhances working performance in healthy older adults.^[33]

Furthermore, in a study conducted by Jake et al. (2012), a positive correlation was found between moderate exercise and short term memory.^[34]

These research works suggest that if certain conditions are met, some kinds of exercise might give an emergency boost to our working or short-term memory.

9. Exercise and Blood Circulation

All in all, one of the greatest benefits of exercise to the memory and larger mental health has to do with blood circulation.

Research works have shown that (moderate) exercise lowers blood pressure and improves circulation^[35][36], and because of this, exercise might be a means to indirectly improve mental health since it can make more oxygenated blood reach the brain and also lower the risk of brain-damaging stroke.

Considering the research works quoted above, we can see that exercise positively affects our brain in a number of ways. We need not say that if you want a better brain or memory, you should consider doing physical exercise.

Interestingly, walking (a form of exercise) might be all you need to keep your brain sharp and get the good effects of exercise. Walking may be the best tonic for your brain. To learn about how walking affects your brain, please read this article.

Aerobic versus Anaerobic – Which One Is Best For Your Brain?

Generally, aerobic exercises appear to be more beneficial to the brain than anaerobic exercises ^[37]. However, more research works need to be done to confidently say which one is best.

That said, we recommend you start with aerobic exercise if you are considering improving your memory. We have given this recommendation because most research works that we have accessed show the benefits of aerobic exercise on the brain and not that of anaerobic.

As for which aerobic exercises are the best, more research works need to be done.

In a nutshell, if you want a better brain, involve yourself in aerobic exercises such as walking, long-slow run or swimming.

Recommendations – Please Read!

If you have an underlying health condition (either serious or mild), it is extremely important you consult your doctor before you take up an exercise routine. This information should not be used as a substitute for a recommendation from a qualified health practitioner.

For most healthy people, though, doing exercise should be completely harmless if precautions are taken and risky behaviors are avoided.

Also, please note the following:

1. Keep to all safety precautions and obey extant rules and laws of your jurisdiction regarding outdoor exercises before you initiate an exercise routine.
2. Make sure you always wear the correct exercise gear and avoid risky behavior when participating in outdoor physical activity.

3. Lastly, if you are planning to engage in an exercise in a natural environment setting, keep yourself away from the harm of insect bites and animal attacks.

Conclusion

We believe we have been able to scientifically establish that adequate sleep and exercise are things to include in your life if you want a better memory. Any attempt to improve your memory must necessarily include adequate sleep and exercise. In fact, you can greatly improve your memory just by getting adequate sleep and exercise.

No memory improvement program is complete without the inclusion of sleep and exercise.

In the next chapter, we are going to be looking at the world of memory supplements. You can access it here.

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