The Power of Sleep

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Are you in a committed—or casual—relationship with sleep?

Sleep is one of the most potent, natural healing processes, that we, as humans, have been gifted.

Yet, many people dismiss sleep as important—or even necessary.

Though public health messages have emphasized the importance of eating a healthy diet and regular exercise, I’d venture to say that getting enough quality, restorative sleep is the most important pillar of achieving optimal health, which includes having a strong immune system and maintaining a healthy weight.

Every biological process that keeps us alive—from hormone balance; metabolism (including appetite, cravings, ability to lose weight, fat-burning and body composition) and immune function; to brain health; mood; cognition; productivity; and performance—is dependent on our body consistently getting enough quality sleep.

In my practice, the reasons people give for going to bed waaay past midnight include:

“I’ve always been a ‘night owl’.”

“I don’t enjoy sleep…it’s really boring.”

“This is my ‘me time’.”

“This is when I am at my most ‘creative’ and ‘productive’.”

“This is the time I get to catch up on my emails, social media and bills!”

“I’m watching the news, my favorite program(s) or YouTuber.”

“I’m bedridden because of my medical condition—so I spend most of my day in bed anyway—when I go to sleep doesn’t matter.”


Sleep Trends

In working with clients of various ages, what I find interesting is that some of the biggest offenders of poor sleep habits (e.g., going to bed long after midnight) are retirees, in their late 50s, 60s, 70s and 80s! Perhaps, after years of a structured wake-sleep schedule (because of work), it feels liberating to go to sleep whenever…typically after midnight.

A 2018 poll, conducted by the National Sleep Foundation, found that only 10% of American adults prioritize their sleep as a health goal—compared to other lifestyle habits, like fitness/nutrition, work, social life, hobbies or personal interests (1).  Only 27% get the recommended 7-9 hours of weekday sleep; over two-thirds (65%) get less!

In 2020, the psychological distress experienced worldwide during COVID lockdowns also worsened sleep patterns: there were changes in quantity and quality of sleep. In a study, published in Sleep Health, sleep patterns were assessed for 6,882 participants, aged 18-94, from 59 countries during the lockdown—and compared to pre-COVID sleep patterns. The results: 58% of participants reported going to bed later or much later than usual; 51% of participants reported they woke up later or much later than usual; 31% reported sleeping less than usual; and, 39% of participants had trouble falling asleep more than usual (2).

We’re BUSY! Why does sleep matter?

For starters, sleep is essential for our survival.

Sleep allows the body to repair and recharge.

Many biological processes also take place only during sleep, including:

    • Muscle growth.
    • Tissue repair.
    • Protein synthesis.
    • Release of growth hormone, a hormone that promotes growth of the body in children and adolescents. In adults, growth hormone influences sugar and fat metabolism; helps maintain body composition; and helps stabilize blood sugar (3).
    • Brain detoxification and brain processing, including learning, memory, decision making, focus, concentration and problem-solving (4)
      Emotional regulation, which affects mood.

In the fall and winter, the body naturally wants to conserve energy, and getting enough quality sleep is a very important part of this process. Rather than pushing through—and ignoring—our fatigue, there are 7 compelling reasons we want to prioritize sleep:

1.  Strengthen the immune system!

Studies of totally sleep-deprived mice showed that these mice lost all of their immune function and died in a matter of weeks (5). Similarly, poor quality sleep and sleep loss (5 hours or less of sleep) is associated with lower immunity in humans (adults) and greater susceptibility to colds, viral infections and respiratory infections (6). In adolescents, short sleep (6 hours or less) is associated with increased risk of cold, flu, gastroenteritis and other infectious diseases (7).

2.  Maintain a healthy weight or lose weight.

If you have unwanted belly fat despite regular exercise and healthy eating habits…look to your sleep!  Sleep deprivation and/or poor sleep disrupts various hormones that regulate metabolism and appetite, contributing to weight gain. Two hormones, in particular, get thrown out of whack: insulin, the hormone that regulates blood sugar, and cortisol, the stress hormone that promotes fat storage, especially around the belly!

Having good sensitivity to insulin indicates that your body is responding properly to insulin. Poor sleep, however, changes how your body produces and uses insulin, and you can become “insulin resistant”. This means that your body has a problem metabolizing glucose, which can lead to Type 2 diabetes, high blood pressure and weight gain. At the same time, lack of quality sleep increases cortisol levels. And when stress hormones are high, you are gifted those unwanted pounds, most visibly around your mid-section.

3.  Feel good—naturally. (Lower risk of depression and anxiety).

Although disturbed sleep is considered a “symptom” of depression, it is a two-way street. Disrupted or fragmented sleep and sleep deprivation contribute to the development of depression. For example, “the graveyard shift” (working between 11PM and 8AM) is strongly associated with mood disorders among night shift workers because their working hours go against the natural sleep-wake cycle, resulting in chronic sleep loss (8).

Less sleep = greater anxiety—and can trigger or worsen anxiety-induced disorders, like panic disorder and PTSD (9).

4.  Detoxify the brain and optimize brain function.

When you get enough sleep, your brain can properly detoxify by removing cellular “trash”—metabolic waste proteins, like beta amyloid (its accumulation in the brain is associated with Alzheimer’s)—that build up in the brain throughout the day. This brain-cleaning process may reduce the risk of Alzheimer’s (10).

5.  Increase focus and productivity.

It is difficult to focus, digest new information and pay attention to details, especially in a fast-paced environment, when we’re tired.

Sleep has a tremendous effect on how our brain processes information. Studies suggest that the quantity and quality of sleep has a profound effect on learning, memory, and processing of information. Not getting enough quality sleep affects mood, motivation, judgment, and our perception of events (11).

Sleep deficiency is characterized by the following factors:

    • Not getting enough sleep,
    • Sleeping at the wrong time of day
    • Fitful sleep and/or not experiencing deep sleep.
    • Having a sleep disorder (obstructive sleep apnea) that prevents you from getting enough sleep or quality sleep.

According to the CDC, at least 1 in 3 adults in the U.S. reported not getting enough sleep, and this has consequences for both employees and employers.

Employees who are sleep-deprived are more likely to make more errors or have accidents because of impaired reaction times (12). Being sleep-deprived can also trigger feelings of irritability or anger, causing you to overreact when interacting with co-workers.

Insomnia is a sleep disorder characterized by trouble falling asleep, staying asleep or an inability to get good quality sleep. When a study of insomnia and its effect on work performance was conducted on a national sample of 7,480 employed adults (in the U.S.) who subscribed to a health plan, an estimated 23.2% reported insomnia. Insomnia was strongly associated with 11.3 days of lost productivity among these poor sleepers (13).

6.  Lower risk of heart disease.

Studies have found strong associations between sleep deficiency and cardiovascular problems,including high blood pressure, coronary heart disease, heart attack, and stroke.

Hypertension. Studies have found that “short sleepers”, those who sleep less than 6 hours/night are up to 32% more likely to develop hypertension compared to those sleeping 7–8hours (14).

Coronary Heart Disease. Short sleepers (< 6 hours sleep) have a higher risk of heart attack risk. In a large national sample of post-menopausal women, those who reported sleeping 5 hours (or less) and 10 hours (or more) had a 25% to 43% increased risk of CHD, or coronary heart disease (15).

Stroke. In a study of 9,692 stroke-free British participants, aged 42 to 81, researchers followed up with participants after 9.5 years. During this period, 346 strokes had occurred. Interestingly, short sleepers (<6 hours sleep) had an 18% increased stroke risk compared to long sleepers (>8 hours) who had a 46% increased stroke risk. Those who reported persistently long sleep or sleeping significantly more had at least double the stroke risk compared to those who slept between 6-8 hours (16).

7.  Build stress resilience.

Sleep affects the body’s central stress response system, which is the hypothalamic-pituitary-adrenal axis, also known as the HPA axis.

When you get enough quality restorative sleep, you are better able to tolerate and cope with stressors.

The three parts of the HPA axis include the hypothalamus (the forebrain; responsible for hunger, thirst and body temperature); pituitary gland (the master gland that controls all the endocrine glands in the body) and adrenal glands, two walnut-sized glands above the kidneys, that produce the stress hormone cortisol, as well as sex hormones, like estrogen and testosterone. Like a symphony, all three parts of the HPA axis work together to regulate your stress response, immune system, digestion, metabolism, mood and energy levels.

HPA dysfunction changes the timing and frequency of when cortisol (the stress hormone) is released. When cortisol levels are high (due to stress) at night, this activates other stress hormones and this HPA “hyperactivity” can negatively impact sleep, resulting in less deep (restorative) sleep, sleep fragmentation (light sleep and frequent waking), and overall shortened sleep time (17).

Sleep deprivation creates HPA axis dysfunction, which is popularly referred to as adrenal fatigue, although this term is not technically accurate. In a study of 26 healthy adults, aged 22-49, who completed a 3-night laboratory experiment, half of the participants were sleep deprived; half were not (the control group). Sleep deprivation was associated with elevated cortisol levels at rest (no stressor) and exaggerated cortisol levels with an actual stressor (18).

Symptoms of HPA dysfunction may present as: daytime sleepiness, excessive fatigue, greater hunger, mood issues (e.g., quickness to anger or irritability), weight gain and more accidents.

Click Below to Continue Reading About Sleep and Health:

How to Fight 7 Common Sleep Robbers, (Part 2)



1  National Sleep Foundation. 2018 Sleep in America Poll. Mar. 12, 2018

2.  Sleep Health. Vol. 7. Issue 2. April 2021. Pgs. 134-142.

Cleveland Clinic. Human Growth Hormone. June 21.2022.

4, 11   Healthy Sleep. Division of Sleep Medicine at Harvard Medical School. Sleep, Learning and Memory. Dec. 18, 2007.

5, 6, 7  Garbarino S, Lanteri P, Bragazzi NL, Magnavita N, Scoditti E. Role of sleep deprivation in immune-related disease risk and outcomes. Communications Biology. 2021 Nov 18;4(1):1304.

8  Al-Abri MA. Sleep Deprivation and Depression: A bi-directional association. Sultan Qaboos Univ Med J. 2015 Feb;15(1):e4-6. Epub 2015 Jan 21

9  Mellman TA. Sleep and anxiety disorders. Psychiatr Clin North Am. 2006 Dec;29(4):1047-58; abstract x.

10  Science. Sleep Drives Metabolic Clearance from the Adult Brain. Oct. 18, 2013, Vol. 342, Issue 6156, pp. 373-377

12  Sleep Foundation. The Link Between Sleep and Job Performance. Sept. 22, 2022.

13  Kessler RC, Berglund PA, Coulouvrat C, Hajak G, Roth T, Shahly V, Shillington AC, Stephenson JJ, Walsh JK. Insomnia and the performance of US workers: results from the America insomnia survey. Sleep. 2011 Sep 1;34(9):1161-71.

14, 15  Covassin N, Singh P. Sleep Duration and Cardiovascular Disease Risk: Epidemiologic and Experimental Evidence. Sleep Med Clin. 2016 Mar;11(1):81-9.

16  Leng Y, Cappuccio FP, Wainwright NW, Surtees PG, Luben R, Brayne C, Khaw KT. Sleep duration and risk of fatal and nonfatal stroke: a prospective study and meta-analysis. Neurology. 2015 Mar 17;84(11):1072-9.

17  Bush, Bradley, ND. The Role of Cortisol in Sleep. Natural Medicine Journal. Jan. 28, 2014.

18  Minkel J, Moreta M, Muto J, Htaik O, Jones C, Basner M, Dinges D. Sleep deprivation potentiates HPA axis stress reactivity in healthy adults. Health Psychol. 2014 Nov;33(11):1430-4.

Hi, I’m Kathryn Matthews. As a Board Certified Functional Health Coach, I help clients reclaim their energy, vitality and well-being. I want you to feel empowered about taking charge of YOUR health! To learn more, see About Kathryn.

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