If living a long, healthy life is something that you strive for, then optimizing your sleep should be a non-negotiable lifestyle habit which tremendously impacts your health and longevity. This is one wellness aspect that I’ve been really focused on over the last year or so when I started having issues sleeping.


I used to get such yummy, restful sleep for 8-9 hrs almost every night for as long as I can remember (besides those 3 years that I worked graveyard). Did you guys know that most Americans carry around a 20,000 hr sleep debt by the age of 40?! Crazy, right?!

So, since this topic is pretty complex, I’ve split it up into 2 parts. In Part 1, we’ll go over why sleep is so important, and Part 2 will include habits and tools you can start to use and implement on a daily basis to optimize sleep.

The Science of Sleep

Circadian Rhythm & Hormones

The circadian rhythm is a natural process (also seen in animals and plants) that involves physiological changes in the body in response to the day and night cycles. In other words, you can think of it as your internal clock that is set by the rising and setting of the sun.

The sunlight naturally wakes us up. Part of this is due to the photoreceptors in our eyes and on our skin that are triggered by the sunlight, which then stimulates the release of cortisol, which is what wakes us up. Cortisol is a hormone that is secreted by your adrenal glands (which sit right on top of your kidneys). These glands play a role in many physiological processes in the body including your stress response, metabolism, and your immune system. Cortisol levels are highest in the morning. When light enters the eyes, it enters a part in the brain called the suprachiasmatic nucleus (SCN), which then tells the brain to turn on or off melatonin (hormone that induces sleep in response to darkness) production. This science is called “chronobiology”—the study of biological rhythms.

When the sun starts to set, your cortisol gradually drops, and you start to relax in preparation for sleep. Unfortunately, we live in a time where we are exposed to so much artificial light in the evening (especially blue light from our cell phones), that our cortisol levels are too high, and melatonin levels are too low during the nighttime hours, in turn, disrupting our sleep. The blue spectrum light is very strong in artificial light sources and shuts down the brain’s production of melatonin.

When we wake up with the sun, we also get a boost in our mitochondrial function (which produces more energy) as well as the number of mitochondria within the cells. Additionally, getting morning sunlight primes the production of serotonin (the hormone/neurotransmitter that has several functions, one of which is energy regulation). If our serotonin levels are inadequate it will lead to a reduction in melatonin, which is essential for the production of melatonin. Melatonin is a hormone that is secreted by the brain that helps us function optimally with our circadian rhythm. When we stay up late, our bodies produce 38% less melatonin. When melatonin is high, cortisol is low, as melatonin shuts its production down. So, in essence, getting sunlight on your skin and eyes increases the production of melatonin at night. When the sun sets, the excess serotonin will then get produced into melatonin allowing for our much needed restful sleep.

Melatonin is released around 7-10 pm and rises and stays elevated until around 4 am. Around 11 pm, we get a spike in growth hormone, which is released by the pituitary gland, until around 3 am. This period is also when your body should get into deeper stages of sleep. When you reach these deeper stages, we have these delta waves in the brain, which allows regeneration of the brain. We also have blood flow increased to the muscles, reduction in inflammation, and repair of connective tissue. This process happens only between the hours of 11pm-3 am. Then, at about 3 am, the body slowly prepares to wake up and cortisol then starts to rise, and spikes at 6 am, which allows you to get up and start the day. 

Melatonin plays a role in our immune system as well. If we are low in melatonin, we won’t have that fast-acting responsive immune system. One reason why children are more resilient with COVID, and other viruses is that they produce a lot more melatonin, and sleep a lot more for regeneration and repair of their cells.

Sleep & Brain Health

Many important physiological functions occur during sleep. There is a massive amount of blood flow to the brain while you sleep. Here are 2 vital neurological functions that occur during sleep:

  1. The brain consolidates memory during sleep:
    • It transforms our short-term memory into long-term sustained memory—this happens when we reach the deeper stages of sleep.
  2. The brain cleanses itself during the deeper stages:
    • There are deposition of byproducts that occur in the brain since it is such an active organ. So, we literally have a “janitorial system” in the brain that gets activated when we sleep.
    • This janitorial system is known as the glymphatic system, which gets stimulated during sleep and gets rid of these unwanted byproducts. (The glymphatic system is the lymphatic system in the brain—What is your lymphatic system?? It is a system that is comprised of organs, lymphatic vessels, and lymph nodes. Similarly to your blood vessels, it is also found throughout your whole body. However, instead of blood, the lymphatic vessels contain what’s called, lymphatic fluid, which is a clear fluid that is drained from blood vessels into your tissues. This fluid carries white blood cells which fight off infections, and fluid from your intestines gets dumped into your lymphatic system as well. The fluid flows largely in one direction by way of valves which keeps the fluid flowing upward toward the neck. Along its path, it flows into the many lymph nodes throughout the body, which is where the fluid is filtered and cleansed of toxins and waste products. The lymph fluid is ultimately dumped into either the left or right subclavian vein (which lie right around your collarbones), which then re-enters the blood circulation to be further filtered by the kidneys. Unlike your blood vessels, the lymphatic fluid is not mobilized by way of a pump (being your heart), the flow of lymphatic fluid relies heavily on the contraction of your muscles, which then squeeze the lymphatic vessels allowing the fluid to flow. So, this is yet another super important reason to perform some kind of physical activity daily to help your body “take out the trash!”)
    • So, if you don’t sleep, your short-term memory does not get converted to long-term memory, and dementia can ensue from the accumulated byproducts that should be “washed out” of the brain if you are getting proper sleep.

Just remember, from 10pm to 2 am, psychological repair occurs; and from 2 am to 6 am, physical repair occurs. You don’t want to miss out on any of these crucial healing processes, so aim to sleep within these hours on a daily basis.

Consequences of Sleep Deprivation

Poor sleep can cause dysfunctioning of your frontal lobe and make you more susceptible to lower level habits, in other words—"survival habits,” which are habits that cause you to crave sugar, and fats and other unhealthy foods. Ghrelin (hormone that induces appetite), and and leptin (hormone that suppresses appetite) levels will be unbalanced and your satiety will be compromised. When you get a good night’s sleep, even your will power is stronger and will allow you to make better food choices and lifestyle habits. People who sleep less than 5 hours a night will have higher ghrelin and lower leptin levels. Sleep deprivation and inactivity have the same level of risk on developing insulin resistance.

Most of the time, if you feel like crap after waking up after a full night’s sleep, it means your body is still trying to cleanse itself of toxins. So, when you finally eat breakfast, you start to feel better because your body shifts from detoxification to digestion. However, you also need to support the continuation of the detox process in the morning by drinking lots of water, having a normal bowel movement (more to come on this!), or even exercising (aids in lymphatic drainage) before you eat breakfast if your current health status permits.

How Disrupted Sleep Makes You More Insulin Resistant and Raises your Blood Sugar

According to studies done on shift workers, if people have disrupted sleep, they have higher levels of inflammation—elevated CRP (inflammatory blood marker), higher insulin resistance, oxidative stress, and their reward centers in their brain are elevated and have an increased susceptibility to carb cravings. As previously mentioned, ghrelin is increased, lectin is decreased, and cortisol levels are elevated. Obesity is one of the main causes of poor sleep.

You actually specifically crave REFINED carbs the next day because these give you a boost of feel-good hormones as it stimulates the reward system in the brain. The elevated cortisol and stress response is what drives carb cravings. Additionally, if we eat late, it actually increases our stomach acid by two-fold, making us more susceptible to acid reflux!

If people have disrupted sleep, they have a higher set point of cortisol and more rapid rise in cortisol during the morning hours. (Cortisol is said to be your longevity hormone.) If you don’t get enough sleep, your body sees that as stress, so the body’s stress response will then release cortisol, thus the high levels in am. People who have better sleep have a lower set point of cortisol and slower rise of cortisol in the am.

There was a study done on 21 healthy people where they disrupted their sleep for 39 nights in a row, and found that this group of people had a 32% decreased insulin response (insulin is the hormone that ushers your blood sugar (glucose) into your cells to use for energy), and decreased metabolic rate. So, imagine how much it would be for those who aren’t healthy!

I hope this has helped illuminate why good quality sleep is so vital to our well-being, and how even "one" night of poor sleep can negatively impact your metabolic and immune health. Please stay tuned for Part 2 of this topic: Sleep Hygiene Recommendations.



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