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Why We Sleep

The question arises of what exactly is the purpose of sleep.  The short answer is that we don’t know exactly.  However, as the science of sleep progresses, our understanding as to the true purpose of sleep will likely be elucidated.

The fact that in deep NREM sleep physical and mental activity slow down considerably, has led to the reasonable speculation that this phase of sleep serves as a recovery and recharging function. While lower species don’t have REM sleep, almost all species do have NREM suggesting that this phase of sleep has a restorative function. When you’re in NREM you’re recharging your batteries. More specifically, N3 sleep or deep sleep is felt to be the most restorative.

This recharging function is essential because a prime consideration of both the brain and body is energy production and conservation. The brain’s prime goal is survival and its primary defense system, the fight/flight system, uses a lot of energy. Thus the production and conservation of energy is a critical function and it is assumed that NREM fills this role. When people are deprived of NREM sleep they do continue to feel very tired and the body tries to compensate for this on subsequent sleep occasions.

If NREM is about energy conservation, what is REM? Paradoxically REM uses a lot of energy. Perhaps the NREM phase of recovery, mentioned above, is among other things, designed to ensure that there’s enough energy for the REM phase?

Some researchers have argued that because of the high energy output in REM, the energy conservation of sleep overall is pretty small, particularly compared to being awake and just resting. Others have pointed out that if restoration of energy was the purpose of sleep, large animals should require more sleep, but in fact they sleep less.

One view of the energy consuming REM phase of sleep is that its main function is the consolidation of memories formed during the day. This would be crucial for learning and indeed young children do seem to require more REM than adults. One metaphor that might be useful here is that during the REM phase of sleep, the brain is filing away the day’s events. As you open the relevant filing cabinet you will see other associated ideas and other relevant recent events and their associations. If that were the case, our dreams would involve recent events and associations these events have with past experiences. Of course, a lot of dreams are like that. Moreover, the dreamer’s emotional state at the time of the dream would likely shape the dream sequence. So it’s likely that some consolidation of memories occurs during REM sleep and this process helps to explain dreaming.

While the consolidation of memories might be an efficient use of sleep time, it doesn’t appear too critical to functioning. As mentioned above, many species don’t even have a REM sleep phase, and when REM is suppressed it doesn’t appear to affect basic functioning.  However, in humans, when REM is suppressed for while, as in heavy alcohol consumption, there is a period after the REM suppression in withdrawal, during which there is increased amounts of REM sleep, what is called REM rebound.

The evidence is not overwhelming but it is reasonable to assume that NREM sleep serves some energy restoration function and that NREM sleep serves some neural consolidation of memories and learning.

Now we have a better understanding of sleep, it has allowed us to research sleep patterns and determine the type, rate and costs of poor quality sleep, reduced sleep time, or a combination of both. And we have been unable to expose the myth, common until about 20 years ago, that sleep deprivation or poor quality sleep doesn’t cause serious health and economic consequences.

History of Sleep

Galen

History of Sleep
While it seems obvious that humans have slept throughout their history, the way they did so in the past might be different from how we sleep today. For example, in his famous Oddysey written around 800 BC, Homer writes about people having two very distinct periods of sleep at different times of the 24 hour cycle. About three hundred years later, the Greek Alcmaeon observed that blood seemed to be draining from the vessels as we sleep, and assumed that this was a cause of it. Similarly, around 400B.C., Hippocrates noted that bodies cool during sleep and that sleep was therefore characterized by blood retreating from the periphery. Not long after that, Aristotle suggested that sleep was brought on by the warming of the body through digestion. Of course, such an observation would be heavily influenced by what one was eating and drinking and certainly rich foods and plentiful amounts of wine could have people nodding off in no time.

Up until about 162 A.D., the view was that the heart, not the brain, was the center of influence from which all bodily actions were controlled. It was Galen who suggested that the brain was the body’s control center and not the heart, leading to sleep theories that were centered on brain rather than heart activity. Subsequent research suggests that the ancients weren’t totally wrong about the heart. It turns out that there are about 50,000 neurons (brain cells) in the heart that connect with the brain. And there are 500 million neurons in the gut, so perhaps Aristotle’s connection between sleeping and eating wasn’t entirely off the mark.

Despite Descartes’ effort during the Renaissance to divide mind and body, much of the subsequent work focused on the brain’s control of the sleep process. In 1650, Dr. Willis identified the functions of different parts of the brain; in 1929, Hans Berger invented the EEG, which opened the study of the brain and its activity. Later, various areas of the brain were identified with the specific functions of sleep.

Specific identification and treatment for sleep disorders emerged in the twentieth century. In 1903 the first sleeping pill was introduced and in 1930 the first stimulant treatment for narcolepsy was developed. Restless Leg Syndrome (RLS) was first described by a Swedish doctor in 1945 and other conditions were subsequently diagnosed; for example, Dr. Schenk and colleagues first reported on a group of patients who didn’t demonstrate the usual muscle paralysis when in REM. In the last seventy years, there has been even more research, which has been able to identify the different stages and phases of sleep.

Nathaniel Kleitman was one of the pioneers of sleep research, with an interesting personal history. Arriving in New York as a penniless 20-year-old in 1915, he went on to get a PhD and conduct some of the earliest research on sleep and the brain. Using a crude EEG machine that used about half a mile of paper each time it ran a sleep test, Kleitman noticed the different stages of sleep, especially dreaming sleep. In a 1953 paper, he and his colleague, Eugene Aserinsky, called this stage of sleep “Rapid Eye Movement.” Kleitman, who lived to be 104, was fascinated by the concept of wake/sleep cycles and even conducted research on the effects of sleeping in caves and submarines.

One of Kleitman’s proteges, William Dement, continued the tradition of researching the brain and sleep using EEG technology. Dement was interested in sleep dysfunction and has contributed enormously to the diagnosis and treatment of sleep disorders. He is widely considered the father of sleep medicine. He launched what is now known as the American Academy of Sleep medicine and served as president for twelve years. Dement also played bass as a jazz musician and has even played with musical greats, Ray Charles and Quincy Jones.

Dement formed the Stanford University Sleep Disorders Clinic which has been the home to a great deal of important sleep research and some other very influential researchers. One of these is Christian Guillemenault, a prolific researcher, who has written more than 600 academic papers. His most noted work has been on the subject of sleep apnea. He co-opted cardiologists to measure and observe blood pressure and cardiac function in people who have what we now know as sleep apnea. In fact, Guillemenault was one of the first to use the term ‘obstructive sleep apnea’ and was the first to use tracheostomies to free the airways, both providing relief to sufferers as well as convincingly demonstrating the relationship between apnea and cardiovascular function.

Despite the work of these pioneers, sleep medicine research and literature lagged behind that of the other key lifestyle behaviors, like nutrition and exercise. It is only in the past decade has there been a recognition of the importance of sleep, elevating it to a science more in keeping with its importance.

What is Sleep?

 

What is sleep?

Regardless of the various theories, we know that sleeping is a natural function common to all humans and animals, too. We are designed to function on a wake/sleep cycle, although with the advent of artificial light (thank you, Edison for the 1879 introduction of the light bulb), energy boosting drinks, foods and medications, that cycle can be severely disrupted. However, it is clear that daily sleep is the preferred default setting for humans and that sleeping serves some very important functions that underpin health and wellbeing. However, there isn’t a complete agreement on what the functions of sleep actually are.

Sleep can simply be described as a state of reduced sensory and environmental responsiveness and physical inactivity. By comparison, wakefulness is characterized by, sensory perception, thinking, environmental responsiveness and physical activity.

There are various stages of sleep in mammals; the two most prominent are Rapid Eye Movement (REM) and non-REM (NREM) sleep. These two phases are quite different.

In REM sleep, muscles are effectively paralyzed, what is called atonia, and dreaming occurs. Obviously, it’s a good design feature to be paralyzed while dreaming otherwise many of us would be sleep walking and acting out or dreams with physical actions. This atonia is achieved through muscle inhibition by parts of the brain that regulate movement.    Interestingly, there is a sleep disorder called REM Behavior Disorder which is characterized by individuals acting out their dreams.

In REM there is also an increase in breathing and heart rate variability. In addition, in REM the brain also uses a lot of energy, which is important because one theory of sleep is that it is about energy conservation, which might seem paradoxical. There is obviously a lot of mental activity in REM unlike in the other sleep phase, which has earned the REM phase of sleep “paradoxical sleep.”  Core temperature is less well regulated in REM but sexual arousal is common and independent of dream content. In other words, physiology comes first and arousal is experienced, which may or may not be incorporated into a dream’s content.

NREM sleep is characterized as featuring general immobility, regular respiration and heart rate, and slow mental activity. It is divided into three parts:

N1: falling asleep, just in that border between nodding off but still easily awoken

N2: breathing and heart rate slow as you drift off to sleep

N3:  the slow wave delta phase that characterizes NREM. The hallmark feature of N3 sleep is slow, high amplitude delta waves on EEG.  The first episode lasts 45-90 minutes but gets progressively shorter though the night. Children tend to have more N3 sleep than older individuals.

These two phases of sleep are so different that they have led to speculation that there is more than one function of sleep and those functions are represented by these quite different states.

In addition to these separate and distinct sleep states, there is also a typical pattern of sleep in humans as we move in and out of these different phases.

Brain Wave Activity

Delta: 1-4 cycles per second: Deep sleep. Typical NREM phase

Theta: 5-8 cycles per second: Conscious, but low level of brain activation, e.g. meditation.

Alpha: 9-13 cycles per second: Relaxed wakefulness

Beta: 14-30 cycles per second: Active processing, stress.

Sleep Cycles

Sleep occurs in cycles that typically last 90 minutes; the ultradian sleep cycle.  Sleep proceeds from NREM phase to a REM phase, about five times a night. There is typically more NREM in the earlier part of sleep and more REM in the later part of the night or early morning. This is why people commonly awaken during their dreams.  REM accounts for between 20% and 25% of total sleep time.

The way in which a person cycles through these phases, as well as the quality of the stages of sleep, determines the healthiness or otherwise of sleep. There are almost 80 distinct types of sleep disorders, which reflect different dysfunctions in the stages and phases of sleep.

Sleep and Alzheimer’s Disease

Overview

We know that several physical health problems, such as cardiovascular issues, have been linked to a lack of sleep. It is also known that sleep disorders can result in or be caused by mental health conditions, especially major depression.

What isn’t so clear to the general population is if there’s a link between sleep and dementia disorders such as Alzheimer’s disease. This article will discuss important aspects of Alzheimer’s disease and then review how sleep may impact this type of dementia.

History of Alzheimer’s disease

The first case of Alzheimer’s disease was identified in 1901 by German psychiatrist Alois Alzheimer in a 50 year old woman he called Auguste D.1 For most of the 20th century, Alzheimer’s disease was reserved as the diagnosis of those between 45 and 65 years of age demonstrating clinical features of dementia. Patients over 65 with dementia were diagnosed as having senile dementia, but this was changed in 1977 to be included as part of Alzheimer’s disease. Alzheimer’s disease is therefore used to describe a specific type of dementia in all ages.

Alzheimer’s disease is the most common type of dementia affecting up to 65 percent of all known cases. In 2015, it was estimated that nearly 30 million people worldwide were living with Alzheimer’s dementia, and the disease resulted in nearly 2 million deaths that year alone.2

In developed countries, Alzheimer’s disease is one of the most financially burdensome diseases.3 In the United States alone, this dementia costs the country nearly $100 billion every year, which makes it the third most expensive disease in this country. As society ages, so will the incidence of Alzheimer’s disease. This illness will therefore, on a yearly basis, end up being more costly to each affected country. Medications used to help reduce some of the symptoms of the dementia may help to decrease the financial costs associated with the disease.

Not only does Alzheimer’s disease place a heavy burden on a country’s financial resources, but it also places a heavy load on the caregivers and the their social structures.4 It has been noted that patients with severe Alzheimer’s disease need daily assistance. Since many do not have the financial means to hire nurses and nursing homes to look after their loved ones, the burden falls to the family members to care for these individuals. Time and time again it’s demonstrated that caring for patients with Alzheimer’s disease can lead to increased stress and anxiety, with subsequent depression, in some family members who support these patients. This is why support groups are available for family members who look after Alzheimer’s patients, and they are urged to make use of the services of these groups.

The cause of Alzheimer’s disease

Alzheimer’s disease is a neurological condition where the nerve cells of the brain are affected. Under certain circumstances, the nerve cells deteriorate gradually over time due to damage inflicted on them. This is referred to as progressive deterioration of the cerebral cortex of the brain. On MRI and CT scans, doctors can actually visualize how atrophied (shrunken) the brain looks because of the loss of these nerve cells in the brain.

The reason why the nerve cells in the brain are affected is due to certain proteins that clump up together and then attach themselves to and damage the brain tissue. The proteins involved here are called beta-amyloid and tau. Normal proteins called APP are found on the surface membrane of the nerve cells, and in Alzheimer’s disease there are enzymatic actions which result in these APP proteins breaking down into smaller fragments. These fragments are the origin of the beta-amyloid proteins.5

Exactly how these beta-amyloid and tau proteins are produced and aggregate to cause Alzheimer’s disease is not clearly understood.  The hypothesis is that they clump together and causes plaques and tangles that lead to nerve cell damage and brain atrophy.

The benefit of sleep

Researchers have discovered that sleep helps to consolidates long-term memories in the brain. One excellent article though looks at another benefit of sleep and how the lack of it can result in neurodegenerative disorders.

During sleep, the brain tries to maintain metabolic homeostasis. In other words, the brain tries to balance the fluids in the organ so that proper functioning and activity of the brain can remain constant. It was demonstrated in the study that during sleep, there was a 60 percent increase in the interstitial space (space between the brain and the membranes that covers the organ), and this allowed for an exchange of the fluid in this interstitial space and the cerebrospinal fluid (fluid found around the spinal cord and brain). The researchers called the space where the exchange took place the glymphatic system, and it is mediated by glial cells in the central nervous system.

The major discovery was that exchange between the two fluids increased the rate of clearance of beta-amyloid proteins, which are associated with the development of Alzheimer’s disease. It was therefore discovered that the restorative function of sleep helps to remove potentially neurotoxic proteins that accumulate during the wakeful state of the neurological system.6

Conclusion

It’s clear that Alzheimer’s disease has an enormous financial and social impact. More importantly though, is that the disease can cause severe stress and anxiety which can lead to more severe complications in close family members who look after their loved ones diagnosed with this dementia.

Most believe that beta-amyloid proteins are a the main reason behind the development of Alzheimer’s disease.  Since sleep helps to clear out these potentially harmful proteins on a nightly basis, it is quite possible that a good night’s sleep can aid in preventing or reducing the risk of developing Alzheimer’s disease?

Patients who therefore struggle with their sleeping habits seem to be at an increased risk of developing Alzheimer’s disease. It’s important then that individuals with sleeping disorders seek help and are managed appropriately to help reduce this risk.

References

  1. Maurer Ulrike; Maurer Konrad (2003).Alzheimer: The Life of a Physician and the Career of a Disease. New York: Columbia University Press. p. 270.
  2. GBD 2015 Disease and Injury Incidence and Prevalence, Collaborators. (8 October 2016). “Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015.”Lancet. 388(10053): 1545–1602.
  3. Economic Considerations in Alzheimer’s Disease. Pharmacotherapy. 1998;18(2 Pt 2):68–73; discussion 79–82.
  4. 4. Clyburn, L. D., Stones, M. J., Hadjistavropoulos, T., & Tuokko, H. (2000). Predicting caregiver burden and depression in Alzheimer’s disease. Journals of Gerontology Series B: Psychological Sciences and Social Sciences55(1), 2.
  5. Hooper NM. Roles of Proteolysis and Lipid Rafts in the Processing of the Amyloid Precursor Protein and Prion Protein. Biochemical Society Transactions. 2005;33(Pt 2):335–38.
  6. Lulu Xie, Hongyi Kang1, Qiwu Xu, Michael J. Chen, Yonghong Liao, Meenakshisundaram Thiyagarajan, John O’Donne, Daniel J. Christensen, Charles Nicholson, Jeffrey J. Iliff, Takahiro Takano, Rashid Deane, Maiken Nedergaard (2013). “Sleep Drives Metabolite Clearance from the Adult Brain”. Science.342 (6156): 373–377.

Sleep and Diet

Obtaining a good night’s sleep is vital to maintaining good health. Without adequate quality sleep, an individual will begin to suffer both mental and physical deficits. In this situation, many individuals complain to their doctors and receive with a prescription for hypnotics or other sleeping pills.

While this might be a helpful for people with certain sleep disorders such as insomnia, it is not an ideal approach.  Some call it a ‘band aid approach’. In fact, many sleep issues can be improved with simple dietary changes.

How can my diet affect my sleep?

When our bodies are in a state of homeostasis, this means that all of our biological systems are functioning in equilibrium with each other. Homeostasis is the optimal state for anyone to live in, and when your body isn’t functioning at its best, it can be hard to get a good night’s sleep. Unfortunately it’s quite difficult to maintain homeostasis in the world we live in.

Poor diet, pollution, inactivity, and many other factors contribute to an imbalance of our body’s natural enzymes and neurotransmitters (those little chemicals that activate the receptors in our brain cells to modulate our body’s systems) and our ability to metabolize and process nutrients.

The best way to maintain homeostasis to eat a healthy diet, regular exercise, and adequate good quality sleep. However, if you’re experiencing sleeping difficulties, it’s quite possible that you’re deficient in a select few nutrients.

Which sleep disorders can be improved with good nutrition?

There are many sleep disorders, many nutrients, and a substantial amount of variance among individuals.  This means that these suggestions can’t guarantee that your sleep problem will be improved – but very likely, you’ll be much healthier!

  • If you suffer from non-restorative sleep, you may be deficient in calcium, vitamin C, or simply dehydrated. You may also have a diet that contains too much fat or cholesterol, or an excess of butyric acid.
    • Citrus fruits contain high amounts of vitamin C
    • Dark leafy green vegetables contain significant amounts of readily-absorbed calcium
    • Rancid butter is a source of butyric acid – make sure your butter’s not expired!
  • If you suffer from somnolence (excessive tiredness) you may be consuming excessive calories or fat – or not enough. Don’t start dropping calories from your diet, unless they come from non-nutritional sources like junk food, before consulting your doctor.
  • If you have sleep apnea, and are not overweight (the condition is often present in those who are obese) then you might need to seek medical help. If you are overweight, try to implement a regular exercise routine.  Untreated sleep apnea, particularly when moderate or severe, is associated with an increase in drug resistant hypertension, stroke, irregular heart rhythms and motor vehicle accidents.
    • Sleep apnea disturbs the quality of your sleep and can make it difficult for you to find the energy to exercise. Changing your diet to include more fruit and vegetables should help provide more energy..
  • If you simply sleep too long or too little, quite a few nutrients could be the culprit.
    • People who sleep less than five hours a night have been shown to be low in folic acid, phosphorous, zinc, and selenium, as well as being dehydrated.
    • Long sleepers are indicated to be low in choline, selenium, lycopene and phosphorous, and typically consume more alcohol than shorter sleepers.

 

Dietary tips to improve your quality of sleep

These tips and tricks may not eliminate a sleep disorder, but they can help improve your night’s rest.

  • Spicy foods and dairy: can cause indigestion, which can make it difficult to fall asleep at night. Indigestion also negatively impacts the quality of the sleep that you do get.
  • Eating a big meal at night, a common approach in the west, is not ideal for your sleep schedule.  Your body will be busy trying to digest your large evening meal which can impact the quality of your sleep.
  • Consuming carbs, sugar, or caffeine within a couple hours of going to bed can keep you up tossing and turning. They stimulate neurotransmitters that are responsible for promoting wakefulness.
  • Drinking alcohol might knock you out, but a drunk sleep (passing out) is not a good sleep. Alcohol commonly changes the sleep architecture so that the ideal restorative benefits of a good night’s sleep are not realized.  More specifically, on nights when alcohol is consumed, individuals commonly wake up after the alcohol has been metabolized and will have difficulty returning to sleep.

The best nutrients for people with sleeping issues

The following nutrients and antioxidants have been shown to help promote healthy sleep:

  • Lycopene is a powerful antioxidant typically found in fruits or vegetables that are red, like watermelons, guavas and papayas.
  • Folate is found in leafy greens as well as avocados and legumes.
  • Phosphorous can be found in tofu, nuts and seeds and legumes.
  • Selenium is best found in whole grains
  • Vitamin D is best found outside your window! If you don’t live in a sunny area, whole grains, mushrooms and fish are other good sources.
  • Vitamin C is found in many of fruits and vegetables from leafy greens to sweet apples and oranges.
  • Choline is an important neurotransmitters that’s best obtained from lean meat, fish and dark leafy green veggies.

The bottom line:

A diet rich in plant based whole foods such as fruits, vegetables, grains and legumes can help restore homeostasis and decrease bodily inflammation and disease.  Along with regular exercise and good sleep, one can better achieve optimal health.  The pillars of good health are diet, exercise and sleep.

Personal note:

For years, I have followed a plant based whole foods diet, also known as a vegan diet.  There is substantial evidence this decreases the likelihood of cardiovascular disease and some cancers.

However, one should be aware that a vegan diet can be very unhealthy particularly if one consumes simple sugars and processed foods.  For me, being a vegan feels right for health, environmental and ethical reasons.

Sleep and Mood Disorders

Sleep disturbances are commonly occurring complaints in people who are diagnosed with mood disorders.1 By far, the most common mood disorder is depression.  It is estimated that 6.7% of the US adult population meets criteria for major depression each year.  The majority of individuals with major depression will have sleep related complaints of complaints of fatigue.

Changes in patient’s sleeping patterns are criteria which help to make the diagnosis of these mood disorders. This emphasizes the importance of how common these sleep disturbances occur in patients with mood disorders. Up to 16 percent of the general population struggles with insomnia (the inability to fall asleep), but this percentage increases in patients with mood disorders.  It is estimated that up to 80% of patients diagnosed with major depression have symptoms of insomnia.  In addition, the symptoms of sleepiness, fatigue, anhedonia, and difficulty initiating or maintaining sleep are very common in both insomnia and depression.  Therefore, the diagnosis of major depression should be made with caution in patients who don’t present with this sleep disorder.2

Major depression

Major depression is characterized by at least two weeks of low mood that is present in most situations. Affected individuals may also complain of experiencing low self-esteem, low energy, a loss of interest in activities that used to be enjoyable, and pain without a definitive cause. Some people may also admit to thinking false beliefs they believe are true (delusions), or they may even hear or see things that others cannot (hallucinations).

Major depression negatively affects an affected person’s personal and work, or school life, as well as their general health, eating and sleeping habits.  One of the main characteristic of major depression is that it affects the hypothalamus in the brain. This is an area of the organ that is responsible for connecting the brain to the endocrine system (responsible for the release of hormones which control metabolic functions of the body). Major depression negatively affects the hypothalamus and this is why patients experience disturbances to their eating habits, sex drive and sleeping patterns. Most of the time these aspects are depressed, but there are cases where they become elevated.

Up to seven percent of patients with major depression die from committing suicide. In fact, a study discovered that clinically depressed patients with insomnia and hypersomnia (increased sleep) had higher scores on the SADS suicide questionnaire than those without any sleep disturbances.3 It was also noted that patients with sleep disturbances were much more likely to become suicidal than those without sleep-related problems.

Sleep apnea and mood disorders

Certain sleep-related conditions may also be associated with the development of mood disorders such as major depression.

This includes sleep apnea, which is a condition associated with difficulty in breathing while the affected individual is sleeping. This disturbance in the person’s ability to breathe results in decreased oxygen supply to the body with resulting sleep fragmentation and injury to body tissues.   We have also seen snorers ‘gasp themselves’ awake.  This is an example of sleep fragmentation which prevents people with sleep apnea from achieving deep restorative sleep.

Researchers have discovered that sleep apnea is associated with the development of certain mental health issues, especially major depression.4  This link suggests that patients with mood disorders should be evaluated for sleep apnea.

Management of sleep disorders in major depression

The optimal approach to managing individuals with mood disorders and insomnia is to consider them comorbid disorders and treat them both.  It is quite possible that managing an individual’s depression will improve their insomnia.  Similarly, it is quite possible that managing an individual’s insomnia will help their depression symptoms.  However, the optimal approach is to address both.  The management of sleep disorders in patients with major depression can be performed by treating the cause of the depression, or by managing the symptoms of the sleep disturbances.

The two main methods of treating insomnia (with or without depression) are with cognitive behavioural therapy and with medications.  Similarly, the two main ways to treat depression is with therapy and with medications.  As expected, there can be a lot of overlap.  Therapy for both insomnia and depression is optimally provided by a behavioural medicine provider with expertise in sleep disorders.   This approach attempts to change behaviours and beliefs relative to one’s condition.  It commonly takes many months to achieve but can result in long term symptom relief.

Pharmacologic approaches generally utilize antidepressant, anti-anxiety medications and soporific agents to treat the myriad of symptoms.   Mirtazapine and fluoxetine are two of the former mentioned medications which have been shown to reduce stress and anxiety levels, associated with the development of major depression. Mirtazapine though has been shown to help more than fluoxetine in managing the insomnia associated with depression.5

Benzodiazepines and benzodiazepine-like medications such as zolpidem have been used for many years to help get patients to sleep. These medications don’t treat the sleep disorder, but they do help to sedate the patient so that they can get to sleep.   Over the past decade, there has been a tremendous increase in the number of sleeping pill prescriptions.  Along with that, there has been an increase in the number of night time falls, particularly in the elderly.  Sleeping pills should be utilized at a minimum, with extreme caution and with close oversight by the managing physician.

Some medications that are commonly prescribed for the treatment of depression may however worsen insomnia and impair full recovery from the illness.2 Therefore, caution needs to be exercised when these patients are prescribed medications by their doctors, and that the individual’s unique circumstances are considered when doing so.

Home remedies and natural measures

Alternative therapies such as the use of certain herbs and dietary supplements are noted to be effective in the management of sleep disturbances in the presence of major depression.6 Such products include St. John’s wort and kava to help with the depression caused by anxiety, and valerian for insomnia specifically.

Preliminary evidence from certain studies shows that supplements such as folate, phenylalanine and tryptophan have shown some benefit in improving the effect of conventional antidepressants. Also, omega-3 fatty acids (from fish oil) have shown to have mood stabilizing effects.

It’s important to remember that any natural supplement should be discussed with the patient’s primary care physician to make sure that these products are safe to use, and that they won’t interact with any other medications that may be used by the patient.

Relaxation measures such as deep breathing exercises, aromatherapy, massage therapy, pet therapy, meditation, prayer, yoga and acupuncture are all proven natural measures which can be incorporated to reduce stress and anxiety levels in people.7 Regular aerobic exercise has also been proven to promote a healthy body which also helps with stress relief.  In my personal life, I am certain that daily exercise and meditation as well as aromatherapy and a healthy diet promote my sense of well-being and improve my sleep

Sleep hygiene is suggested to help patients to get to sleep regardless of the cause of the insomnia. These include measures such as going to bed and waking up at the same time every day, following strictly to a pre-bedtime routine, taking a warm bath or shower before retiring to bed, only lying in bed to try to sleep and not watching T.V. or reading a book, and staying in bed even if the patient wakes up during the night.8

Conclusion

Sleep disturbances are very common problems in patients with mood disorders.  Optimal management involves addressing both the mood disorder and the insomnia/sleep condition in parallel utilizing a combinations of behavioural modification/therapy, medications and natural therapies.  One should think of it as a ‘two way street’.  Improving one’s sleep will improve one’s mood problems.  Similarly, improving one’s mood disorder such as depression will commonly improve the quality of sleep.

 

  1. Peterson, M. J., & Benca, R. M. (2006). Sleep in mood disorders. Psychiatric Clinics29(4), 1009-1032.
  2. Antonina Luca, Maria Luca, & Carmela Calandra (2013). Sleep disorders and depression: brief review of the literature, case report, and nonpharmacologic interventions for depression. Clin Interv Aging, 8, 1033–1039.
  3. Ağargün, M. Y., Kara, H., & Solmaz, M. (1997). Sleep disturbances and suicidal behavior in patients with major depression. The Journal of clinical psychiatry58(6), 249-251.
  4. Sharafkhaneh, A., Giray, N., Richardson, P., Young, T., & Hirshkowitz, M. (2005). Association of psychiatric disorders and sleep apnea in a large cohort. Sleep28(11), 1405-1411.
  5. Winokur, A., DeMartinis 3rd, N. A., McNally, D. P., Gary, E. M., Cormier, J. L., & Gary, K. A. (2003). Comparative effects of mirtazapine and fluoxetine on sleep physiology measures in patients with major depression and insomnia. The Journal of clinical psychiatry64(10), 1224-1229.
  6. Fugh-Berman, A., & Cott, J. M. (1999). Dietary supplements and natural products as psychotherapeutic agents. Psychosomatic Medicine61(5), 712-728.
  7. Arcos-Carmona, I. M., Castro-Sánchez, A. M., Matarán-Peñarrocha, G. A., Gutiérrez-Rubio, A. B., Ramos-González, E., & Moreno-Lorenzo, C. (2011). Effects of aerobic exercise program and relaxation techniques on anxiety, quality of sleep, depression, and quality of life in patients with fibromyalgia: a randomized controlled trial. Medicina clínica137(9), 398-401.
  8. Harvey, A. G. (2000). Sleep hygiene and sleep-onset insomnia. The Journal of nervous and mental disease188(1), 53-55.

Sleep and aging

Sleep changes dramatically over our life spans.  As we know, newborns sleep the majority of the day and napping persists until age 3-4.  Eventually, our sleep consolidates into a single period of sleep lasting 7-8 hours per night.  Elderly individuals seem to be more prone to distressing sleep disruptions.  This blog post reviews the types of sleep issues that commonly occur as we age.

The effect of age on sleep

We have discussed the effects of decreased sleep on the elderly, and now we shall focus on what the effect a person’s age has on sleeping patterns.

A study has shown that elderly people experience a shorter duration of sleep time, decreased sleep efficiency, and increased waking up at night independent of other factors such as chronic conditions and problems such as sleep apnea.8

The study further found that in men, age was independently associated with more Stage 1 and Stage 2 sleep and less Stage 3 to 4 (slow wave sleep) and REM sleep. Older women were found to have more trouble falling asleep, and experienced more issues with waking up during the night and waking up too early.

Lack of sleep and dementia

One of the vital roles of sleep is to allow the brain to activate a specific system that is responsible for cementing long term memories in the brain cortex. Sleeping also helps individuals to retain information and perform better on memory tasks and activities.1

Studies have shown that sleep deprivation may be linked to the development of dementia disorders, such as Alzheimer’s disease, in the elderly.2 The reason behind this may be due to lack of slow-wave sleep causing the build-up of beta-amyloid proteins in the brain, which ultimately affect the mentioned system responsible for memory consolidation. Alzheimer’s disease also worsens patients’ sleep patterns, so a vicious cycle develops where sleep deprivation causes worsening of the disease which worsens the patients’ abilities to sleep.

Lewy body dementia, which is caused by deposits of Lewy body proteins on the nerve cells of the brain, directly causes increased daytime sleepiness due to lack of sleep.3 This seems to occur regardless of other factors such as disease progression and memory fluctuations in these affected individuals. Lewy body dementia is also responsible for rapid eye movement (REM) sleep disorder, which is a condition characterized by flailing of the limbs and acting out while dreaming. The reason for this is because REM sleep causes temporary paralysis of the skeletal muscles of the body, and REM sleep disorder inhibits this paralysis causing the patients’ symptoms.4

The researchers of these studies have collectively requested that further investigations are conducted into the cause and effect of sleep disturbances on dementia-related pathologies, in order to try and discover possible treatments for the conditions.

Sleep duration and inflammation

A recent study was done determining the link between the duration of sleep in the elderly and what effect inflammation has on the mortality of individuals aged between 71 and 76 years of age.5 The fundamental findings made were that short sleep duration (5 or less hours of sleep per night) was associated with an increase in inflammatory markers resulting in elevated mortality levels, and that longer sleep duration was associated with decreased mortality. These findings were made independent of other risk factors such as smoking, obesity, chronic conditions such as hypertension (high blood pressure) and diabetes (uncontrolled high glucose levels), and complications of these factors such as coronary artery disease.

Therefore, shorter sleep duration is regarded as an independent cause of increased mortality, thereby making this aspect just as detrimental to one’s health as the mentioned factors.

Sleep disturbances and depression

A study that was performed on a community of elderly people yielded that these individuals’ disturbed sleeping patterns were linked to them experiencing varying symptoms of depression.6

The sleep-related issues were linked to those who were female, living alone, unmarried and who had a disability. The two year follow up analysis of these elderly individuals showed that half of the participants still experienced sleep disturbances. It was discovered that the best predictors for future depression were elderly people with sleep disturbances and current depression symptoms; and for those who were not initially depressed, it was sleep disturbances alone.

This latter finding suggests that disturbed sleeping patterns are not only a symptom of depression, but rather as a possible predictor of the future development of depression in the elderly.

Sleep disorders and falls in the elderly

Since sleep-related disorders and falls are a common problem in the elderly, researchers decided to look into the possible link between the two problems.

Surveys were conducted which were filled in by elderly people between 65 and 89 years of age, and most of the participants admitted to falling down when getting up at night. The reason for the latter issue was that the individuals were experiencing poor sleep quality.7 Other risk factors for the falls included the use of diuretics, causing the affected participants to get up and visit the bathroom at night, not being able to see properly and bumping into obstacles, and having to use walking aids for pre-existing physical issues.

Improving sleep in the elderly

Due to the abovementioned issues it would seem prudent to promote an adequate amount of sleep, especially in the elderly who are more prone to developing issues such as dementia and who already have an increased risk of mortality.

A study has shown that supplementing with melatonin, a hormone produced by the pineal gland in the brain and which regulates the sleep-wake cycle, helps to promote an adequate amount of sleep in affected individuals.9

Elderly patients who are prone to sleep disorders have been noted to be those who are on chronic medications. These medications can disrupt the production and clearance of melatonin by the body, thus resulting in the sleep-related issues experienced by the affected individual.

Conclusion

The recommendation made by the researchers, in the clinical studies used for this article, is that an adequate amount of sleep of between six to eight hours is achieved by elderly people. Less than 5 hours and more than 9 hours of sleep can have detrimental effects on the physical and psychological well-being of these individuals.

 

  1. Scullin, M. K. (2013). Sleep, memory, and aging: the link between slow-wave sleep and episodic memory changes from younger to older adults.Psychology and aging,28(1), 105.
  2. Drummond, S. P., & Brown, G. G. (2001). The effects of total sleep deprivation on cerebral responses to cognitive performance.Neuropsychopharmacology, 25, S68-S73.

3. Ferman, T.J., Smith, G.E., Dickson, D.W., Graff-Radford, N.R, Lin, S-C., Wszolek, Z., … & Boeve, B.F. (2014). Abnormal daytime sleepiness in dementia with Lewy bodies compared to Alzheimer’s disease using the Multiple Sleep Latency Test. Alzheimer’s Research & Therapy, 6, 76.

  1. Iranzo, A., Molinuevo, J. L., Santamaría, J., Serradell, M., Martí, M. J., Valldeoriola, F., & Tolosa, E. (2006). Rapid-eye-movement sleep behaviour disorder as an early marker for a neurodegenerative disorder: a descriptive study.The Lancet Neurology,5(7), 572-577.
  2. Hall, M. H., Smagula, S. F., Boudreau, R. M., Ayonayon, H. N., Goldman, S. E., Harris, T. B., … & Stone, K. L. (2015). Association between sleep duration and mortality is mediated by markers of inflammation and health in older adults: the health, aging and body composition study.Sleep,38(2), 189-195.
  3. Livingston, G., Blizard, B., & Mann, A. (1993). Does sleep disturbance predict depression in elderly people? A study in inner London.Br J Gen Pract,43(376), 445-448.
  4. Hill, E. L., Cumming, R. G., Lewis, R., Carrington, S., & Couteur, D. G. L. (2007). Sleep disturbances and falls in older people.The Journals of Gerontology Series A: Biological Sciences and Medical Sciences,62(1), 62-66.
  5. Hill, E. L., Cumming, R. G., Lewis, R., Carrington, S., & Couteur, D. G. L. (2007). Sleep disturbances and falls in older people.The Journals of Gerontology Series A: Biological Sciences and Medical Sciences,62(1), 62-66.
  6. Garfinkel, D., Laudon, M., Nof, D., & Zisapel, N. (1995). Improvement of sleep quality in elderly people by controlled-release melatonin.The Lancet,346(8974), 541-544.

Does sleep protect us from illness?

We have all heard that getting more sleep decrease the likelihood of getting sick?  On the flip side, we know that illness commonly makes us tired but does sleep help us recover quicker?  By examining the medical literature, this blog post will attempt to answer these questions.

It is no secret that sleep rejuvenates our bodies and is essential for proper body functions.  For many years, the effect of sleep on the immune system was largely criticized and considered far-fetched. However, in recent years, many studies have investigated the relationship between a good night’s sleep and the effect it has on the immune system of the body. Although the literature does not define an exact mechanism for enhanced immunity associated with sleep, the evidence of a connection is quite clear.

The Immune System

Before discussing the studies, a primer on immunity is needed.  Our immune system protects our bodies from a disease and infection. It is triggered by a harmful stimulus or stress, which causes increased production and growth of the immune cells.  This system consists of a range of immune cells that protect the body from harmful antigens. The major cellular components are white blood cells (or leukocytes). Some of the white blood cells also produce protein based substances called cytokines which play an integral part in the immune response.

Cytokines are further classified in many subtypes. One of the types of classification divides cytokines into pro-inflammatory cytokines that include Interleukin-1 and Tissue Necrosis Factor (TNF), and anti-inflammatory cytokines that include Interleukin-4, Interleukin-13 and Interleukin-10.

All of the mentioned immune components can be affected by sleep and sleep loss.  In our discussion of the relationship between sleep and immunity, we will explore these cell types and mediators.

The Effect of Sleep on the Immune System

Now that we have discussed the different types of immune cells, we will consider how the individual component is affected by a good night’s sleep.

In a study conducted by Uthgennannt [2] and Schoolmann, 13 healthy men were asked to spend two nights in the sleep laboratory. Lights out was 11 pm and the subjects were allowed to sleep for 3.5 hours. They were then asked to stay awake till 7 am, when blood was sampled. In another condition, the subjects were asked to stay awake between 11 pm and 3 am and then permitted to sleep for 3.5 hours. Blood was sampled every 30 minutes.  In the first condition, when the subjects were allowed to sleep at night, there was a decreased amount of pro-inflammatory cytokines, TNF-alpha and Interleukin-1, while opposite results were observed for those who stayed awake.

In other studies, the serum level of Interleukin-7  which is involved in the maturation and migration of immature T-lymphocytes was observed to increase during the Slow Wave stage of sleep, with a subsequent rise in naïve T-lymphocytes themselves. [1]

Another study conducted by Matsumoto [5], on a 24-hour wake period, demonstrated a marked decrease in cytotoxic NK cells, important cells of inflammation.  In addition, there was a decrease in anti-inflammatory cytokines such as Interleukin-10.

Although the levels of cytokines fluctuate, and the exact pattern is pretty complex; in a nutshell, the main pro-inflammatory cytokines decrease during nocturnal sleep (usually in Slow Wave Sleep stage), whereas the levels of T-lymphocytes and cytokines that are involved in the growth and differentiation of T-lymphocyte as well as those that take part in adaptive immunity (more later) increased. This reflects that sleep, indeed, has a positive effect in boosting the immunity of our bodies since it allows for some cells and cytokines to peak levels while keeping other components at bay.

Another aspect of immunity that is theorized to enhance during sleep is the formation of immunologic memory. Normally when a person is infected by a particular pathogen, immune cells memorize the response.  By forming antigen specific antibodies, the body reacts more rapidly to any subsequent attacks by the same pathogen. Studies have revealed that subjects who stayed awake after a hepatitis A vaccine shot demonstrated lower levels of antigen-specific antibody titers compared to those who received the vaccine and slept regularly [1]. This proves that not only does sleep help in enhancing the cellular elements of the immune system, but it also helps in the formation of immunologic memory.

Adaptive Immunity vs. Innate Immunity

Numerous studies have established that sleep has a direct effect on adaptive immunity, and less so on innate immunity.

Innate immunity involves the protection against a foreign antigen by the body’s defense mechanisms that do not include the antigen-specific immune cells. These defense barriers include the skin, chemicals in the body and cytotoxic immune cells. Adaptive immunity is more complex and encompasses the reaction of antigen-specific immune cells which includes recognizing the antigen, releasing a cascade of immune cellular components and mediators, and finally removing the pathogen.

Research on the decreased levels of Interleukin-6 during sleep which acts as both a pro-inflammatory and anti-inflammatory agent and takes part in innate immunity suggests that innate immune response is less affected during sleep. Similarly, the serum level of interferon-alpha that plays a core role in the innate immune response against viral infection also declined during sleep. On the other hand, Interleukin-7, an important mediator of adaptive immunity, showed a marked increase during sleep. [6]

The Effect of Prolonged Wakefulness on the Immune System

While inflammation is an early response to infection, an inflammatory response unchecked can be detrimental. Several studies have looked at the relationship between sleep deprivation and immunity. The results of these studies were fairly consistent that the levels of the immune cells were impacted by sleep quantity.

Blood samples from individuals subjected to prolonged wakefulness showed a marked increase in inflammatory mediators such as interleukin-6 levels, pro-inflammatory cytokines, TNF-alpha, interleukin-1 and C-reactive protein [7] An increase in these pro-inflammatory cells made the subjects more vulnerable to stress. In addition, the elevated levels of these inflammatory markers is associated with cardiovascular disease and type 2 diabetes. [1]

Does Sleep Decrease the Likelihood of Getting Sick?

Although the relationship between sleep and immunity is still being researched, many studies indicate a strong relationship between a proper sleep/wake cycle and improved immunity of the body.  There is little doubt that a good night’s sleep can decrease the likelihood of getting sick.

 

References

  1. Besedovsky, Luciana, Tanja Lange, and Jan Born. “Sleep and immune function.” Pflugers Archiv. Springer-Verlag, Jan. 2012.
  2. Uthgenannt, D., D. Schoolmann, R. Pietrowsky, H. L. Fehm, and J. Born. “Effects of sleep on the production of cytokines in humans.” Psychosomatic medicine. U.S. National Library of Medicine, n.d.
  3. Sarosh J. Motivala, Michael R. Irwin. “Current Directions in Psychological Science”Vol 16, Issue 1, pp. 21 – 25, June 24. 2016
  4. Dinarello, C. A. “Proinflammatory cytokines.” Chest. U.S. National Library of Medicine, Aug. 2000.
  5. Matsumoto Y, Mishima K, Satoh K, Tozawa T, Mishima Y, Shimizu T, Hishikawa Y. Total sleep deprivation induces an acute and transient increase in NK cell activity in healthy young volunteers.Sleep.2001;24:804–809.
  6. Dimitrov S, Lange T, Nohroudi K, Born J. Number and function of circulating human antigen presenting cells regulated by sleep.Sleep.2007;30:401–411
  7. Meier-Ewert HK, Ridker PM, Rifai N, Regan MM, Price NJ, Dinges DF, Mullington JM. Effect of sleep loss on C-reactive protein, an inflammatory marker of cardiovascular risk.J Am Coll Cardiol.2004;43:678–683.

Sleep and Memory

For many years, scientists have been trying to understand the connection between sleep and memory. A multitude of research, experiments and studies have been conducted for this purpose, however the underlying mechanism of this connection is still a question mark. Although there is no clear mechanism by which sleep affects our memory, there is no denying that the two are interrelated.

Before we jump into the theories that have been proposed by researchers on this topic, we first need to be familiar with the different types or stages of sleep, as well as the types of memories first.

SLEEP: REM vs. Slow Wave Sleep

Relative to sleep, we need to better understand 2 of the 4 stages of sleep: Rapid-eye-movement (REM) and Slow-Wave Sleep, also known as deep sleep. The two stages occur alternatively with marked changes in the brain waves. The characteristics of deep sleep as seen on an EEG are high amplitude and low frequency brain waves and deep sleep tends to occur more towards the beginning of the night. Dreaming in this stage is rare, and if dreaming does occur, it is usually forgotten once you wake up.

REM sleep, on the other hand, predominates in the second half of the night as the body becomes more and more rested. True to its name, REM sleep is characterized by muscles twitches and eye movements as well as vivid dreaming. Brain waves on the EEG during REM sleep show low amplitude, high frequency waves.

MEMORY: Declarative vs. Non-Declarative

Long-term memory is broadly categorized in two forms: Declarative and non-Declarative. One basic difference between the two forms is whether or not the hippocampus is involveda part of the brain’s limbic system) is involved or not. [1] Declarative memories encompass those that can be easily recalled and consist of the knowledge of facts and events, involving visual and verbal input. Declarative memory itself is divided into semantic memories, the knowledge of facts and world events, and episodic memories that store more personal, autobiographical information. Neuronal circuits in the hippocampus are an integral part in the formation of declarative memories.

Non-declarative memories, also sometimes referred to as procedural memories, are those that store a person’s memory of a skill. [3] This includes all types of ‘how to do’ memories such as cooking a particular dish or playing the piano. Unlike the former type, non-declarative memory does not involve the active participation of brain cells in the hippocampus; instead, motor areas in the frontal cortex are involved.

Memory Processing During Sleep

The process of memory formation isn’t as simple as it might seem. While a lot is still unknown about how memories are truly processed in our brains, we do know the process takes place in three core stages: Acquisition, Consolidation and Recall. [1]

The introduction of a particular memory in the brain is known as acquisition. The consolidation stage occurs after the memory has been introduced when it gets further sorted and stored (or consolidated). Finally, the recall process is simply recalling or remembering a stored memory.

Clinical experiments on rats and humans have demonstrated a possible relation between sleep and the consolidation of memories. Acquisition and recall, on the other hand, take place when the person is wide awake. It is hypothesized that one you fall asleep, the acquired memories become consolidated and stored in their final destination. Not all memories are stored in the same area of the brain. According to Dr. Robert Stickgold of the Sleep Department at Harvard, the memory of what you ate for breakfast yesterday is not stored in the same area of the brain where the memory of what your favorite breakfast is stored. It is when you fall asleep that these memories are sorted into their respective places. [3]

A primary question relative to sleep and memory is during which stage of sleep are memories actively processed.  Although a definitive pathway has not been elucidated, studies have suggested a relationship between consolidation of memories (especially the non-declarative type of memory) and REM sleep.

In a recent research study, subjects who were asked to learn a foreign language demonstrated increased periods of REM sleep during the night. [3]  As far as declarative memories were concerned, none of the studies could prove the connection between verbal/visual memories and REM sleep.

This led to the hypothesis that perhaps Slow Wave Sleep had some role in the consolidation of memory, particularly the declarative type. Research is still scarce concerning this theory and the studies that have been conducted show inconsistent findings.

Effects of Sleep Deprivation on Memory

The effect of sleep deprivation on an individual’s memory is a topic that has been explored extensively. Many studies have been conducted where subjects were kept awake for over 35 hours to test the effect sleep deprivation had on their long-term memory. Results showed that a 24-hour sleep deprivation period did not have a significant effect on memory recall.  However, a 35-hour sleep deprivation period results in impaired facial recognition (a type of episodic memory), recall and verbal memory. [3]

Although a relationship was established between sleep deprivation and memory through these studies, we still do not know if it was sleep deprivation that directly affected the neuronal circuitry involved in memory consolidation, or if the effects were more metabolic.

As pointed out in a post in Harvard Health Publications, the effects of too little sleep on memory impairment could be due to other known harmful effects of sleep deprivation on the heart and circulation. Sleep deprived patients usually have a consistent high blood pressure that could directly affect brain cells that consolidate memory. [4]

Improving Memory with Sleep

Several researchers have hypothesized that obtaining the recommended hours of sleep can benefit the individual’s memory. To test this hypothesis, a study was conducted on a group of twenty female and twenty male adolescents, between 10 and 14 years. The group was divided into two – a sleep group, and a non-sleep group. All subjects were given the paired-associate test, a standard for testing declarative memory. The paired-associate test consists of remembering two related (tree/leaf) and two unrelated (tree/shoe) words. In addition, the two groups were given the letter-number test which consists of sequencing a list of mixed numbers and letter in an ascending order.  The sleep group was given the task at 9 pm and was tested at 9 am after a night of sleep. The non-sleep group was given the task at 9 am and tested at 9 pm at night with continuation of normal day activities and without naps. The paired-associate test did not result in any significant differences.   However, utilizing the letter-number test, there was a 20.6% increase in long term memory in the sleep group showed versus the non-sleep group. [5]

Even though the direct effect or mechanism of sleep on memory is still being studied, it is clear that improves cognition and refreshes the body. Therefore, a good night’s sleep is essential for optimal functioning through the day.  Obtaining 7-8 hours of sleep nightly at a consistent time along with proper diet and exercise can greatly contribute to a great night’s sleep.

References

  1. Rasch, Björn, and Jan Born. “About Sleep’s Role in Memory.” Physiological Reviews. American Physiological Society, Apr. 2013.
  2. Alhola, Paula, and Päivi Polo-Kantola. “Sleep deprivation: Impact on cognitive performance.” Neuropsychiatric Disease and Treatment. Dove Medical Press, Oct. 2007.
  3. “Sleep, Learning, and Memory.” Sleep, Learning, and Memory | Healthy Sleep. N.p., n.d.
  4. LeWine, M.D. Howard. “Too little sleep, and too much, affect memory.” Harvard Health Blog. N.p., 29 Oct. 2015.
  5. Potkin, Katya Trudeau, and William E. Bunney. “Sleep Improves Memory: The Effect of Sleep on Long Term Memory in Early Adolescence.” PLoS ONE. Public Library of Science, 2012.

It’s good to breathe

Obstructive sleep apnea can be quite dangerous when not treated.  Restricted airflow which occurs repetitively in individuals with sleep apnea stresses the body in several ways.  We know that people who suffer from obstructive sleep apnea have a higher risk of high blood pressure, stroke, irregular heart rhythms, elevated blood glucose levels, car accidents and even sudden cardiac death.  In addition, people with sleep apnea often feel tired, complain of non-restorative sleep and have a poor quality of life.  Having untreated sleep apnea does not necessarily mean that an individual will ever suffer these ailments, but it does raise the risk.   The more severe the sleep apnea, the higher the likelihood of ever suffering from one of these entities.

Untreated sleep apnea results in these ill effects for two main reasons.  First of all, the oxygen levels dip which stresses the body. The second reason is that sleep apnea results in fragmented and poor quality sleep.

When people don’t breath well at night,  oxygen levels repetitively dip resulting in bodily stress.  As most people are aware, our body tissues need adequate oxygen for optimal function.  It can thought of as a stress test every night.  When a person’s upper airways narrow, airflow is limited and oxygen levels drop.    Most people’s oxygen levels remain at 97-100%.  Associated with apnea events, oxygen levels drop by at least 3%.  It is not uncommon for oxygen levels to drop even further.  Individuals with severe sleep apnea commonly have drops of their oxygen levels into the 70-80% range.  I have seen patient’s with oxygen levels dipping into the 50s%!     When the tissues are starved of adequate oxygen, the risk of heart attack and stroke increases.  The sympathetic nervous system is activated which results in elevated blood pressures with frequent surges in blood pressure and heart rate.   In addition, inflammatory mediators are released which can further damage tissues.

Sleep apnea also results in fragmented  and poor quality sleep.  After a good night’s sleep, a person should feel refreshed and ready for a full day’s activities.  Optimal sleep should last 7-8 hours in adults during which a person cycles through stages of sleep.   There should be 3-4 sleep cycles during which a person transitions from light sleep, to deep sleep and then into REM sleep.  We call this sleep architecture.  Each stage of sleep is associated with important bodily functions like memory consolidation, hormone secretion and clearing of accumulated waste products.   If an individual’s sleep is disrupted by sleep apnea, sleep architecture becomes fragmented and the full benefits of sleep are not achieved.  The breathing events associated with sleep apnea frequently cause arousals.  Essentially, arousals are ‘brain awakenings’ which disrupt sleep architecture.    For example, a person with moderate or severe sleep apnea will commonly have more than 15 arousals per hours which prevents them from entering the restorative stages of sleep such as deep sleep.  This is why a patient with sleep apnea will commonly state that they never feel like they slept.

Indeed, it is good to breathe.  This article explains why obstructive sleep apnea leads to an increased risk of cardiovascular problems, as well as excessive daytime sleepiness.