Importance of Circadian Rhythm

by Jes Williams @feelmoregooder

It’s interesting to observe our modern lifestyles from an aerial view and in comparison to the generations before us. How most of us live is often drastically different from how our ancestors lived. This is not to suggest that living in a cave, departed from everything modern is the solution.

However, it’s time we take a clear look at the implications of these lifestyle changes. According to the CDC, over 50% of the American population has a chronic health condition. This is approximately 129 million people. Why is this significant? It’s something to consider when we think about how, as a populous, we are sicker than ever.

Dr. Jack Kruse connects the dots here, pointing out that the earliest literature on many chronic illnesses coincides with the invention of artificial light, in the 1800s:

“Since 1900 we have been blaming food and a lack of exercise for what modern light caused. The industrial revolution lasted from 1760-1840. This began to change mitochondrial DNA inheritance because people began burying the sun by living an indoor existence causing a spectral deficiency in light radiations.” - Dr. Jack Kruse. As one of the top neurosurgeons in the world, he fervently educates on this, also stating that the rise in unwell human beings “also coincided with the discovery of the light bulb and the AC power grid before quantum mechanic and biochemistry were discovered.”

The consideration of light environment is one that’s so commonly overlooked, undermined, and misunderstood. But, we need to know that light is huge, and our biology is photoentrained and guided by the sun. Conversely, our bodies are also impacted by light that is emitted from artificial sources, especially outside of the time that the sun is up.

Daytime Sunlight

Let’s go through a day of sunlight. Early morning sunlight (before the sun is at about 20 degrees above the horizon), is rich in red and infrared right. These wavelengths are anti-inflammatory and nourishing to your mitochondria. (1)

Exposing your eyes (and as much skin as possible) to this sunlight early in the day also kicks off a hormonal cascade. This happens via the suprachiasmatic nucleus (SCN), which is located on the anterior portion of the hypothalamus in the brain. Light enters the eyes and interacts with the SCN, triggering the production of pregnenalone, which is the precursor to hormones including progesterone, estrogen, testosterone, and more. (2, 3, 4, 5, 6)

Thus, morning sunlight is crucial for optimal hormones. Too, getting sufficient sunlight is linked to an increase of serotonin, as well as prevention of numerous negative health outcomes. (16, 17) Don’t forget, too, that the eyes are a part of the brain. (7) Input into the eyes has big yields, partially because of this.

Honoring Dark at Night

“Ambient nighttime light exposure is implicated as a risk factor for adverse health outcomes.” (11) Light at night is shown to negatively impact insulin sensitivity the following morning. Since we already know that isolated blue light increases cortisol & blood glucose, this is not surprising. (12, 13)

Darkness at night is imperative for our bodies to utilize melatonin (you create subscellular melatonin when exposed to sunlight) and create pineal melatonin to bring you and keep you to sleep. Melatonin is crucial for cell repair, renewal, and helping your body keep up with its “housework”, partially due to its antioxidant properties.

Additionally, there is sufficient literature suggesting that exposure to light during sleep increases one’s risk for numerous negative health outcomes. (14, 15, 18) A few ways to reduce disruptive light exposure at night are getting portable red light lamps, replacing your bulbs to amber and red hues, using candles instead of overnight lights, turning your phone screen red using the color filters feature, and using software called “Iris” on your desktop to minimize your blue light exposure.

You might wonder, why red? Dim red light does not suppress melatonin production like blue wavelengths do. Avoiding bright overhead lights can be especially important, as we have receptors in the bottom part of our eyes that pick up on those overhead photon signals.

Circadian Rhythm

Many of us have heard of the phrase “circadian rhythm”, but it seems to be mostly in the context of getting better sleep. But, it reaches much further than that. In 2017, three scientists who studied the functioning of organisms’ internal circadian clocks won the 2017 Nobel Prize in Physiology or Medicine. This is huge for visibility on this topic. “We expose ourselves to inappropriate light, we travel across time zones, we do shift work, and all of that is negatively impacting our health.” (8)

Furthermore, a 2012 study shows that sunrise and sunset both contain certain light frequencies that communicates to the brain’s master clock (SCN). This study also reveals that, in part, this is due to the blue/yellow contrast present in the sunlight at these times.

So, why is circadian rhythm so important and so heavily implied in this literature and by many forethinking practitioners of present-day? Well, circadian rhythm governs biological functions. As a 2019 study explains, “light can also be used as an effective and noninvasive therapeutic option with little to no side effects, to improve sleep, mood and general well-being.” (9)

Did you know that a weeks worth of camping has to been shown to be sufficient in “resetting” your circadian rhythm? (10) Sounds like we all need to go on a camping trip!

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