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Understanding Sleep in Lifestyle Medicine

Updated: Jun 8, 2021


Ever since I re-launched this website, I started discussing Lifestyle Medicine as a medical discipline and started the six areas of focus with nutrition. Each area of focus is important in itself and these should go along with the others. So enumerating them does not mean that is the order or a pattern to be followed. The next area of focus of Lifestyle Medicine I am going to share today is about sleep.

Isn’t it funny that although everyone sleeps, it is difficult for us to define precisely what sleep is? Try asking people randomly what sleep means to them and you will get different answers. Yet, and this is a reality, sleep is a human activity that almost everyone takes for granted.

Sleep Health and World Sleep Day

Last month, World Sleep Day® was celebrated. Yes, there is such a thing. It is held every Friday before Spring Vernal Equinox each year. For this year, it was held last March 19th. This annual event is intended to be a celebration of sleep and at the same time, create a call to action on important issues related to sleep which includes medicine, education, productivity, driving, and other social aspects of human life.

It goes to show that Sleep Health is being recognized as a component of Lifestyle Medicine. Sleep Health or sleep medicine is relatively new in the field of Lifestyle Medicine that scientific studies and related literature on sleep health are limited. Be that as it may, this article is going to provide you an overview of the key issues associated with sleeping habits and how to incorporate this knowledge into your own lifestyle for better health.

Definition of Sleep

Sleep is a body and mind activity which is natural, recurring, and reversible. It is characterized by altered consciousness, decreased responsiveness to external stimuli, inhibited senses, reduced muscular activity, reduced interactions with surroundings, rapid eye movement, and dreams. It is associated with a typical posture of lying down with eyes closed. Scientists say that during sleep there are brain wave activity changes, as well as changes in the rate of breathing, heart rate, body temperature and other physiological functions. Also, sleep is relatively easy to reverse which distinguishes it apart from coma and other disorders of consciousness.

The Anatomy and Physiology of Sleep

For many centuries, physicians used to believe that sleep was a period of physical and mental inactivity only to realize over the last 60 years that the brain remains active during sleep. In fact, several brain structures are involved in sleep.

The brain’s hypothalamus contains nerve cells that control sleep and waking up. Within the hypothalamus is the suprachiasmatic nucleus (SCN) that receives information about light exposure directly from the eyes and controls your behavioral rhythm. The brain stem (includes the pons, medulla, and midbrain) communicates with the hypothalamus to control the transitions between wake and sleep. A brain chemical called GABA is produced in the hypothalamus and the brain stem. It reduces the activity of arousal centers. The pons and medulla send signals to the limbs and other body muscles to relax so that you don’t involuntarily act out your dreams while sleeping. The thalamus which relays information from the senses to the cerebral cortex becomes quiet, letting you tune out the external world. During REM sleep, the thalamus sends the cerebral cortex images, sounds, and other sensations which make your dreams come alive. The amygdala becomes active during REM sleep because it processes the emotions. The pineal gland receives signals from the suprachiasmatic nucleus (SCN) which increases the production of melatonin, a hormone that puts you to sleep once it gets dark. The basal forebrain promotes sleep and wakefulness, while a part of the midbrain acts as an arousal system. Release of adenosine, a chemical by-product of cellular energy consumption supports your sleep drive.

There are two basic types of sleep: the non-REM sleep and the rapid eye movement (REM) sleep.

The first stage of sleep is a non-REM sleep that changes over from your wakefulness then it slows down to your sleep. This lasts for only several minutes, thus it is short. It is characterized by a relatively light sleep. Your heartbeat, breathing, and eye movements are slow. Your skeletal muscles start to relax with occasional twitches. Your brain waves begin to slow down, too.

The second stage of sleep is also a non-REM sleep which is a period of light sleep before entering the deeper sleep. Your heartbeat and breathing are slow, your body cools down, your skeletal muscles relax even further, and your eye movements stop. Your brain wave activity slows down but with brief bursts of electrical activity. Most of your sleep cycles happen at this stage more than in any other stages.

The third stage of sleep is a non-REM sleep characterized by a period of deep sleep that you need to feel refreshed in the morning. It occurs during the first half of the night and has a longer period. Your heartbeat and breathing are slow at their lowest levels during sleep. Your skeletal muscles are relaxed. This is the stage where it would be difficult to wake you up. Your brain waves become even slower.

REM sleep occurs within the first 90 minutes after you fall asleep. Your eyes move rapidly from side to side behind closed eyelids. Your brain wave activities seem closer to that of your wakefulness. Your breathing becomes faster and irregular, and your heartbeat and blood pressure increase to near waking levels because most of your dreaming occurs at this stage. The arm and leg muscles become temporarily paralyzed preventing you from acting out your dreams.

Process C and Process S

There are two body mechanisms that work together to regulate your sleep: the Circadian regulation (Process C) and homeostatic control (Process S). Although there are other factors affecting your sleep, understanding these two processes will help you strive towards a consistent sleep schedule.

Process C refers to your internal clock, regulated by the suprachiasmatic nucleus (SCN) of the hypothalamus. This clock regulates and controls your 24-hour sleep-wake cycle via the influence of light and melatonin. In the absence of light, as during the evening, melatonin is produced by your body promoting sleep but in the presence of light, your production of melatonin ceases, signaling your brain that it is daytime and you need to wake up. However, your behavior can override these natural signals. For example, bright lights at night shut down your production of melatonin, delaying your sleep until late hours of the night.

Process S promotes your sleep based on the previous amount of time that you spent awake. During wakefulness your brain accumulates substances that promote sleep, when you sleep these substances are cleared up and you feel alert again. This process is particularly important when you take naps in the afternoon, because you deplete the sleep promoting substances and you are not able to fall asleep at a reasonable time in the evening. The best sleep is when you synchronize your sleep/wake times to your internal clock and find a perfect equilibrium between your Process C and Process S.

Why Do We Sleep?

There are numerous theories on why you sleep and no theory will ever be proven correct. However, sleep may be explained by two or more of these theories. By understanding why you sleep, you will learn to respect sleep as a body function and enjoy its benefits rather than taking it for granted.

Inactivity Theory

Also known as the Adaptive or Evolutionary Theory, this suggests that inactivity at night is an adaptation and means to survive especially when you would be vulnerable.

Energy Conservation Theory

According to this theory, sleep reduces your demand for energy and your energy expenditure during the day especially at times when you are not in search of food. This is because your body temperature and caloric demand decreases while sleeping. Studies show that energy metabolism goes down by 10 percent during sleep. This supports the opinion that sleep helps organisms conserve their energies.

Restorative Theory

This theory is based on the belief that sleep restores what your body has lost while you are awake. It provides a time for your body to repair and rejuvenate. There are findings that show muscle growth, tissue repair, protein synthesis, and growth hormone release happen during sleep.

Brain Plasticity Theory

This theory is based on findings that sleep is correlated to changes in the structure and organization of the brain known as brain plasticity. Its connection to sleep has critical roles especially in the brain development among infants and young children and with adults as well. This is seen in the effect sleep deprivation on learning and performance of various activities.

While these theories do not directly answer the question why you sleep, it does set the stage for putting sleep in a new context and generating new knowledge about this essential body activity.

How much sleep do we need?

Some people prefer going to bed early while others have a preference for staying up late. But as mentioned earlier, children need to get more sleep which is essential for proper growth and development. As you age, sleep influences your immune system, memory, attention, hunger, mood, response time, and many other body functions.

The CDC has recommended the number of hours of sleep for every age group. Refer to the image below:

Although individual sleep needs and patterns may vary, most adults usually need seven to nine hours of sleep. If you feel refreshed and energized upon waking up, you are getting enough sleep. But if you’re not, you probably feel sleepy, tired, sluggish, clumsy, forgetful, and even cranky.

The Sleep-Work-Life Balance Challenge

You have twenty-four hours in a day and one-third of that is allotted for sleep and the other two-thirds are for your activities during wakefulness. That two-thirds of a day is still divided into your working hours (mainly, your job) and your time for other activities of daily living (family, personal time, exercise, meals, commute, etc.).

But have you reflected on how you spend your twenty-four hours? Some of you may say no probably because you are too focused on your priorities like your job, or your family’s needs. A few of you would say yes because it has been your habit to track down what you’re doing.

Here is a challenge for you: For one week, try to take note of how many hours of sleep, work, and other activities of daily living you spend in a day. At the end of the week, count the number of hours you spent on sleep. If you get less than fifty hours of sleep in a week, reflect if you felt tired or sluggish most of your waking hours. Most likely you will answer yes and unaware that you already show signs of sleep deprivation.

Here is an example from a journal that shows the sleep-work-life balance:

Impact of Lifestyle and Technology Developments on Sleep

You are living in modern times, and that means you are too busy to sleep. It is increasingly difficult for you to sleep with so many things vying for your attention.


You might be spending many hours in front of your television set everyday. Americans spend more than four hours on average watching TV. That is more than three hundred hours a year spent staring at a bright television screen.

Social Media

Your social media keeps you from getting sleep because you are glued to your smartphones texting, chatting, or engaging on your different social media accounts even on bed.


You value their work that there are times you bring home some of it. Now, you are probably working from home. Both setups affect your sleeping routines. Not only that, the concept of 24/7 company work shifts, or even working on a different time zone affects your sleep and can cause a sleep disorder called shift work sleep disorder.


Jet lag is characterized by difficulty of falling asleep during or after a flight, disrupted sleep, and loss of appetite. Although your friends may tag you as a jet-setter, the negative effects on your health is not “cool”.


You already know that smoking is bad for your health. But smoking also affects sleep. A study shows that smokers sleep less and the quality of their sleep is lower as compared to non-smokers.

Substance Abuse

Some of you might take alcohol or medications just to get some sleep. Others take drugs so as not to fall asleep. These substances affect your sleeping routines severely and also lower the quality of the sleep over time.

Chronic Diseases and Sleep Deprivation

Sleep deprivation is a cumulative effect of not obtaining adequate sleep. It adversely affects the body, brain, mood and cognitive functions and impacts all aspects of health. Excessive daytime sleepiness, fatigue, clumsiness, and weight gain or loss are just several signs of sleep deprivation

Sleep deprivation can also increase your risk of vehicular accidents because lack of sleep can slow down your reaction time and decreased alertness. Also, when you don’t get enough sleep, your ability to fight infection may decrease.

We’ve been saying that chronic diseases are becoming top causes of death and illnesses. And I’ve been advocating that Lifestyle Medicine can reverse these chronic diseases. One of the areas of focus in Lifestyle Medicine is sleep. Therefore, there should be an interest in the role of sleep health in the management of chronic diseases. As per the National Heart, Lung and Blood Institute, insufficient sleep has been linked to the development and management of type 2 diabetes, cardiovascular disease, obesity, and depression.


Studies show that people who habitually slept for only a few hours are not able to process glucose. It seems that sleep duration and sleep quality could be predictors of Hemoglobin A1c levels, an important marker of blood sugar control. This could mean that they are most likely to develop type 2 diabetes. Therefore, it is suggested to optimize your sleep duration and quality in order to improve your blood sugar.

Cardiovascular Disease

Persons with sleep apnea, a sleep disorder, have an increased risk for a number of cardiovascular diseases like hypertension, stroke, coronary heart disease and irregular heartbeats. Also, sleep apnea and atherosclerosis share some characteristics suggesting that sleep apnea may be an indicator of cardiovascular disease.


Research shows that obesity is linked to metabolic changes during a short sleep. Studies conducted also revealed an association between short sleep duration and excess body weight particularly in children. Sleep in childhood and adolescence is important for brain development and insufficient sleep among children may adversely affect the function of the hypothalamus which regulates appetite and food energy expenditure.


There is a complex relationship between sleep and depression. While sleep deprivation has been held as a sign of depression, recent research indicates that symptoms may decrease once sufficient sleep is restored. The study further suggests that it is important to assess the sleep sufficiency of persons with depression and to monitor symptoms of depression among persons with a sleep disorder.

Lifestyle Medicine’s Focus on Sleep

Lifestyle Medicine encourages a systematic approach to lifestyle issues including nutrition, exercise, and stress management. It also emphasizes heightened sensitivity to environmental factors in general and sleep health.

However, conventional medicine’s approach to sleep disorders falls short because they encourage reliance on sedative-hypnotics. This has taught us much about the biomedical view of sleep but it has forgotten the sleeper.

Lifestyle Medicine reduces this reliance on sedatives by (1) restoring our regard for you, the sleeper; (2) significantly expanding the range of effective interventions; and (3) reframing sleep health as a lifestyle issue.

Personalization begins by complementing standard evaluation procedures with an invitation to tell your personal “sleep stories.” Lifestyle Medicine emphasizes the importance of the doctor-patient partnership in healing. It also acknowledges your natural inclination to heal. Lifestyle Medicine has the wide range of evidence-based interventions available for sleep health in terms of sleep aids, relaxation practices, and alternative medical systems. Utilizing these interventions can help address overreliance on prescription and over-the-counter sleep medications. In recent years, practices that have long been staples of Lifestyle Medicine, such as yoga, mindfulness meditation, and breathing exercises, are finding acceptance in more mainstream medicine.

Tips to a Better Sleep

If you are having problems sleeping, here are a few tips:

  1. Establish a regular bedtime and waking time. If you need to set an alarm, that’s fine, just don’t snooze.

  2. Do not exceed 45 minutes of nap or daytime sleep. If you do, you may not be able to follow your established bedtime.

  3. Do not smoke and do not drink excessive alcohol four hours before bedtime.

  4. No coffee, tea, soda, or chocolate six hours before bedtime.

  5. You are allowed to take a light healthy snack before bedtime but avoid eating heavy, creamy, spicy, or sugary foods four hours before bedtime.

  6. If you think exercise will put you to sleep, you’re wrong. You are encouraged to exercise regularly but not before bedtime.

  7. It also helps to have a short tepid or warm shower before bedtime.

  8. Use a comfortable bed and keep your room well-ventilated. Your bed is for sleeping and should not be used for work. If you’re working at home in the bedroom, make sure that your workstation is away from the bed.

  9. Turn off the lights and block out the noise.


Sleep Health is relatively new just as Lifestyle Medicine. Sleep, which is a natural body activity, should never be taken for granted because insufficient sleep could lead to sleep disorders and impact chronic diseases.

If you are having problems with your sleep, feel free to schedule a consultation. I will help and work with you to make changes at whatever pace you are comfortable with. There is a health program that might suit your needs. If you want to hear from me discuss more about Lifestyle Medicine, feel free to listen to my podcast. If you want to be updated with news and features from this website, subscribe to my newsletter or reach out using the contact forms below.


American Sleep Association. 2017. “Sleep Deprivation: Symptoms, Causes, Treatments.” American Sleep Association. May 12, 2017.

Centers for Disease Control and Prevention. 2019a. “How Much Sleep Do I Need?” Centers for Disease Control and Prevention. 2019.

———. 2019b. “Sleep and Chronic Disease.” Centers for Disease Control and Prevention. 2019.

DePietro, MaryAnn. n.d. “Why Is Sleep Important?” American Sleep Association. Accessed March 29, 2021.

Division of Sleep Medicine. 2019. “The Characteristics of Sleep.” Healthy Sleep. Harvard Medical School. 2019.

———. n.d. “Why Do We Sleep, Anyway?” Healthy Sleep. Division of Sleep Medicine at Harvard Medical School. Accessed April 8, 2021.

Levy Andersen, Monica, and Sergio Tufik. 2015. “Sleep and the Modern Society.” Journal of Sleep Disorders & Therapy Volume 4 (Issue 5): 131.

Naiman, Rubin. 2015. “Integrative Medicine Approaches to Insomnia.” Sleep Review. Medqor. August 17, 2015.

National Heart, Lung and Blood Institute. 2018. “Sleep Deprivation and Deficiency | National Heart, Lung, and Blood Institute (NHLBI).” November 5, 2018.

Office of Communications and Public Liaison. 2019. “Brain Basics: Understanding Sleep.” National Institute of Neurological Disorders and Stroke. National Institutes of Health. 2019.

World Sleep Society. n.d. “World Sleep Day.” World Sleep Day. World Sleep Society. Accessed March 29, 2021.

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1 Comment

It would be interesting to hear your thoughts on the studies associated with processes that clear out waste products from your brain during sleep.

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