Sleep is Non-negotiable Medicine: Why we sleep and what happens when we don’t get enough. An Evidence-Based Discussion by Dr. Elena Zarifis, Bsc.(Hons), Naturopathic Doctor
Even flowers (dandelions included!) close up for the evening when the sun goes down.
Sleep is an essential part of our being; integral to our existence. Yet we still don’t completely understand why (1).
There are some theories, and while we don’t have all the answers as to why we sleep, we do know it is important to our health- without question.
One contributing theory, out of many reasons (for example: neuron repair and regeneration), for why we sleep has evolved from newer research on the glymphatic system. That’s right, lymphatic with a ‘G’. This glymphatic system is within our brain, and it has a very critical job of clearing waste metabolites out of our central nervous system. The volume of this glymphatic system increases to 20% volume while we are asleep, compared to only 13% volume while we are awake2. This means the glymphatic system is functioning more while we are asleep.
Adequate, quality sleep is absolutely crucial to our short-term and long-term health and in preventing disease. This is non-negotiable, and we will be covering this throughout this article by discussing how sleep plays a major role in many critical physiological processes, including regulation of many important hormones such as : TSH, Insulin, Cortisol, Leptin, Growth Hormone, and more. In this article we are focused on a few key epicentres of health, but it is important to note that there are many more systems that are affected by sleep than what we discuss here (for example: the immune system, the brain etc).
Our society has trouble sleeping, there is no question about that. Our world moves fast, the demands are high, our stress levels are rising, and technology and screens are in use from when we open our eyes in the morning until we shut them at night. Our environment and lifestyle produces/ inflicts upon us stressor after stressor, to the point where genuine rest and quality sleep have become difficult, purposeful tasks that we have to carve out space and time for, and learn like a honed skill. It should not be this way, but it is.
Thyroid Stimulating Hormone and Leptin
A study that evaluated the effects of sleep restriction on hormones found that a lack of sleep – specifically around 4 hours of sleep- decreased Thyroid stimulating hormone (TSH) levels, and also decreased leptin hormone levels 3.
When leptin is low, our appetite is high. This is because leptin normally signals that we are “full” or satiated. If leptin is low , then our brain is not getting the signal that it is satisfied in terms of food/calories. This makes us feel “hungry”, and we start to crave energy dense(aka high calorie) , nutritionally poor foods- foods that will give us quick and easy energy like simple carbohydrates (think : sugars, hyper-processed foods).
To keep it simple, low TSH levels means our thyroid gland is not getting stimulated enough to produce thyroid hormones that circulate in our body and carry out their actions, like supporting energy production in cells. Thyroid health and thyroid hormones are critical to have in balance as virtually every system and hormone in our body is affected by them. It is also just as important that the rest of our body is in overall good health to respond adequately to the thyroid hormones in circulation- one major factor in achieving this is getting good sleep.
Cortisol and Growth Hormone
During sleep, we have different stages, and in these different stages our physiology is doing different things.
In Stage 3 sleep , which is also called Slow Wave Sleep, we are in very deep sleep, and it is difficult to wake from this3. Getting enough good quality sleep is critical, because in stage 3 sleep , our body secretes Growth Hormone which is important for things like physical repair and learning3. Sleeping is one thing, but sleeping well and reaching adequate deep sleep is another, as studies have shown that growth hormone increases significantly in Stage 3, compared to stage 1 and 2 and REM 4.
Cortisol , our stress hormone, is also a key hormone in our sleep-wake cycle. Cortisol is the hormone that is supposed to spike in the morning, to wake us up and get us out of bed feeling alert and ready to tackle the day. After it spikes high in the morning, it should generally gradually decrease throughout the day, with a minor jump in the late afternoon, reaching its lowest levels overnight, until the next morning when it spikes up again. When this cortisol rhythm is off, and is too high in the evenings/overnight- we have trouble getting restful sleep, or cannot fall asleep.
Specifically, cortisol reduces Stage 3- slow wave sleep3, which in turn reduces growth hormone mentioned above, that is critical for physical repair and learning.
This shows how important stress management and night-time behaviour are for getting adequate, quality sleep.
Lucky for you, Naturopathic Doctors have a lot to offer in stress management and difficulty sleeping, and should be your go-to practitioner for these issues.
Weight Management and the Dangers of ‘Belly Fat’
Quality sleep is also very important in weight management, and more importantly, in the amount of fat tissue that gets stored around our organs. This fat tissue that is stored around our internal organs is called Visceral Adipose Tissue(VAT), and it carries many risks with it. In short, it can increase levels of inflammation, increase risk of cardiovascular disease and is hormonally active- meaning it secretes hormones itself, leading to hormonal imbalances and a cascade of negative effects on health.
People often claim they can function fine on 4-6 hours of sleep, but this is unfortunately not true(except for those with rare genetic chronotypes). The human body is absolutely fine-tuned to adapt for survival mode, but this doesn’t mean it is good for you , or is sustainable.
One study assessed the amount of VAT in both short sleepers- who slept under 6hrs per day, average sleepers, and long sleepers (slept over 9hrs per day)5. People who slept under 6 hr per day , or over 9 h per day, accumulated significantly more VAT 5. The good news is, those that changed from being a short sleeper to average sleeper protected against further VAT gain5.
This increase in VAT from poor sleep could be due to a few things. I discuss two possible theories , out of many mechanisms which may have been at play, below.
Poor Sleep and Weight Gain: Cortisol and The Nervous System
The poor sleep group led to increased VAT, and this is likely because of how poor sleep can negatively affect cortisol management. Cortisol , when too high for too long, causes fat to be distributed viscerally- around our organs, and over time becomes visible as central obesity, commonly referred to as ‘belly fat’. Research shows that nighttime cortisol concentration and sympathetic nervous system (SNS) activity increase during periods of sleep deprivation6. This means that if we are not getting enough quality and duration of sleep, then poor sleep and the stress , anxiety and high cortisol levels that comes with it, can become a vicious cycle.
If your sympathetic nervous system activity is high, your body is not in a state of relaxation and is unable to facilitate or initiate sleep. Poor sleep leads to increased SNS activity, which then makes it harder to sleep the next night- this cycle continues then continues on, and on.
Poor Sleep and Weight Gain: Leptin and Ghrelin
Another theory for the mechanism behind why people would gain more VAT with poor quality sleep relates back to the effect that sleep deprivation has on leptin. More studies have demonstrated that sleep deprivation does not only negatively affect leptin levels, as previously discussed, but also leads to the behavioural changes that are caused by these changes in leptin and other appetite regulating hormones. This behavioural change is a consumption of higher calories7 (please see note at the end of this paragraph). One study measured the levels of leptin and ghrelin in the blood of participants, as well as obtained hunger and appetite ratings, after periods of sleep restriction (4 hours of sleep)7. The results showed that sleeping for only 4 hours lead to decreased leptin, increased appetite and hunger ratings, and increased Ghrelin levels (an appetite stimulating hormone)7. Specifically, leptin decreased by 18%, and ghrelin increased by 24%. In addition, there was a 32% increase in appetite for high carbohydrate content food in those who slept 4 hours7.
These results show that when sleep deprived, people consume more calories due to an increase in hunger and a decrease in satiety (feeling of being full)7.
As a note, this is not to be interpreted that all carbs are bad, or that calorie counting is king. This is simply to demonstrate that poor sleep can affect our appetite regulating hormones and our behaviour , and can make it harder for us to stick to a healthier lifestyle or our goals, as it can drive us towards consuming more hyper-processed foods and an unbalanced diet.
Insulin and Blood Sugar
Sleep is also important in ensuring proper blood sugar regulation. When we eat, our blood sugar rises, and insulin is released to take those blood sugars and put them inside cells to control the amount of sugars in our blood. Sleep deprivation has been shown to increase both insulin resistance , and inflammation8. With insulin resistance, our body is no longer responding to that insulin as well as it used to, so both the sugars and the insulin remain high in the blood instead of being used by cells. This increase in insulin resistance is shown to be two-fold in those with misaligned circadian rhythms8 – of which shift workers would be classified into. Blood glucose control and maintaining insulin sensitivity is an absolute key to health. These mechanisms heavily influence cardiovascular health, skin health, mood regulation, cancer incidence, brain health, eye sight, thyroid health, inflammation levels, hormonal imbalances, diabetes, heart disease, chronic disease etc ….the list just continues on and on.
Blood sugar and sleep are connected in both directions: getting quality sleep is affected by blood glucose control as well! If we don’t have great control over our blood glucose levels, they can dip low enough overnight that it actually causes us to have restless sleep and wake up frequently.
While this article could go on and on and on about why sleep is non-negotiable for health, it won’t! There are many more systems that are affected by sleep than what we discuss here (for example: the immune system, the brain etc). There are varying root causes for each of the following sleep issues, and having just one of these issues is detrimental to your health:
- not sleeping 7-9 hours per night
- not feeling rested in the morning, not feeling refreshed in the morning
- waking up throughout the night in jolts, with anxiety, or frequently (restless)
- having difficulty falling asleep
- having difficulty staying asleep
Your Naturopathic Doctor can help address your sleep issues, and because everyone is different, everyone has unique reasons for why they are having trouble getting adequate, quality sleep. Using individualized Naturopathic Medicine to get to the root cause is key in getting a good quality snooze.
Sleep is influenced by our varying hormones, digestive health, mental health, nutritional status, pain, environment during the day, behaviour during the day, environment of our home and bedroom, past trauma, current stress, activity levels, time of day of activity, what we eat, what we drink, our previous night of sleep … you get the picture.
Sleep is non-negotiable, it is a critical piece of foundational health because it affects so many other key players in health and disease: thyroid health, immune system health, blood glucose control , cortisol levels and sympathetic nervous system activity, visceral fat deposition , inflammation , hormones, growth, learning, physical repair, Brain health etc.
If you want to achieve better health or maintain good health, you will need to sleep well.
If you’re having trouble sleeping well: see a Naturopathic Doctor.
Dr. Elena Zarifis, BSc.(Hons), Naturopathic Doctor
Downtown Oakville, Ontario
Online booking link: drelenaznd.janeapp.com
1: Kim TW, Jeong JH, Hong SC. The impact of sleep and circadian disturbance on hormones and metabolism. Int J Endocrinol. 2015;2015:591729. doi:10.1155/2015/591729
2: -Jessen NA, et al. The Glymphatic System – a Beginners Guide. Neurochem Res. 2015;40(12):2583-2599.
3: Webinar by Dr Catherine Darley. Sleep Physiology, disorders and the adrenal connection. Institute of naturopathic sleep medicine inc. Seattle, WA, USA. Displaying the work of : Van Cauter E, Et Al. Impact of sleep deprivation on hormones and Metabolism, Medscape, Neurology.
4: Holl R. W., Hartman M. L., Veldhuis J. D., Taylor W. M., Thorner M. O. Thirty-second sampling of plasma growth hormone in man: correlation with sleep stages. Journal of Clinical Endocrinology and Metabolism. 1991;72(4):854–861. doi: 10.1210/jcem-72-4-854.
5: Chaput J.-P., Bouchard C., Tremblay A. Change in sleep duration and visceral fat accumulation over 6 years in adults. Obesity. 2014;22(5):E12–E12. doi: 10.1002/oby.20701
6: Spiegel K., Leproult R., van Cauter E. Impact of sleep debt on metabolic and endocrine function. The Lancet. 1999;354(9188):1435–1439. doi: 10.1016/s0140-6736(99)01376-8. (cortisol incr and SNS increase)
7: Spiegel K., Tasali E., Penev P., van Cauter E. Brief communication: sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Annals of Internal Medicine. 2004;141(11):846–850. doi: 10.7326/0003-4819-141-11-200412070-00008. [