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The Sun Sessions: Chronobiology

Hello, I’m Jason Boyd from Bio+Logical Health and Nutrition. I’d like to welcome you to session two of the Sun Sessions. Today we’re going to be talking about chronobiology, or the biological timekeeping structures – or biological clocks – in the human organism that have profound influences on our health.


Chronobiology is a relatively new science – although it’s roots date back to the 18th century. For today’s session, we’ll be discussing how the day-night cycle affects the internal rhythms and overall health of the human organism, what happens when you disrupt or disturb those cycles, and steps you can take to correct them – something called “chronotherapy.”

Circadian Rhythm

Now it’s likely that most of you have heard the term “circadian rhythm” which is the cyclical ebb and flow that regulates our physiology and function and takes approximately 24-hours, such as the sleep/wake cycle. This is one of three cycles of chronobiology, and the one I’ll be discussing today.

Like anything that exhibits or depends on a rhythm for proper function, maintaining the correct timing or flow of that rhythm is crucial; without it you would have chaos. The human body is no different.

When our circadian rhythms aren’t in a homeostatic or balanced state, we create metabolic chaos, which is another name for dis-ease. And in my opinion, this is the number one thing people need to correct if they want to improve or optimize their health – because it affects quite literally every aspect of your physiology.

In humans, our internal time-keeping system consists of our master biological clock called the suprachiasmatic nucleus or SCN, which controls a group of clock genes that exist in nearly every cell in your body.

Now keep in mind that we have trillions of cells; the fact that we have four clock genes inside nearly every one of them telling them when to replicate or divide or repair or die or when to signal or not signal indicates that keeping time – or, entraining our circadian rhythm – is of the utmost importance to our body. And remember, cells are the basic building blocks in humans, which means that tissues, organs, and systems also have clocks and also operate under biological time.


So how does our body, in fact, “keep time”? There are a few different environmental cues – or “zeitgebers” – like temperature and mealtimes, but the primary cue responsible for keeping time is light. It starts with sunlight hitting our eyes.

The photonic energy travels through the eyeball, all the way to the retina at the back, through the central retinal pathway to the hypothalamus – which is known as the brain’s brain – where the master biological clock – the SCN – is located.

Now interestingly, the retina is home to a significant body of DHA receptors. DHA is the omega 3 fatty acid primarily found in marine animals and the main reason why people supplement with fish oil or krill oil.

Why would the back of your eyes contain so many of these receptors?

Role of DHA

Again…it must be important. It seems as though DHA plays a role in converting the photonic energy from light into electrochemical energy – along with a group of light sensitive proteins called opsins – in order to “wind” the SCN and get it telling the correct biological time.

From there, the SCN then sends out the signal to “wind” all the other clocks in your body so that your body’s trillions of cells are all synchronized with one another. Because the SCN is the master clock that controls all others, there’s a need for a stronger DC electrical current at this point to kick things off, and thus, the need for more DHA at the junction where this takes place in order to synchronize the circadian rhythm.

If you’re picking up what I’m laying down here, then it should make sense to you when I say that the eye isn’t used just for visual purposes – it also has non-visual purposes, specifically to function as a clock and help entrain the body’s circadian rhythms.

Ninety-eight percent of the light that enters our body does so through the eyes, and of the approximately three billion sensory inputs our body receives every second, two billion of them happen in the eyes. And since light influences nearly every biological function in the body, that means light is a drug.

So if that’s true, then that also means the frequency of light matters, as does the intensity, timing, and duration – or, as the saying goes, the dose makes the poison.


Okay, so no doubt you understand intensity, timing, and duration of light – or how bright it is, what time of day it is, and how long you’re exposed to it – but what about frequency? I’ll get into a more detailed discussion about some of the characteristics of light in another session, so I’ll keep it brief here for the purposes of today’s session.

The full spectrum of sunlight ranges in frequency from 250-3000nm. In that spectrum, the visible portion ranges from 380-780nm with the lower end being in the blue range and the upper end being in the red range.

Then of course, there are the invisible frequencies – and even though you can’t see them, they most definitely have a pharmacological effect on us. The ones we’re concerned with are the ultraviolet and infrared.

The lower frequencies – the ultraviolet and blue – have greater energy, and thus, have the ability to be more damaging when used incorrectly – although they’re still very beneficial and absolutely necessary. Conversely, the higher frequencies – the red – have less energy and tend to be healing and regenerative.

Now we need and use all frequencies for different reasons, and they all have different effects on our biology. One of the many things light influences are our hormones – including our sex hormones, our hunger hormones leptin and ghrelin, the stress hormone cortisol, insulin and glucose, and the sleep hormone melatonin – although its purpose goes far beyond relaxing us to help us fall asleep.


Melatonin plays a huge role in our circadian rhythms, so it’s worth spending a minute on it.

First, melatonin is synthesized from the neurotransmitter serotonin, which is synthesized from the amino acid tryptophan. It’s made in the eye, skin, pineal gland, liver, and the gut.

In fact, the gut makes about 400x more melatonin than the pineal gland, yet most of it isn’t released into the blood. Instead, it’s used in the gut to help protect against the development of ulcers, GERD, IBS, IBD, and other digestive disorders. It’s worth noting here that because melatonin is synthesized from tryptophan, if you have digestive problems, then you may not be breaking down proteins well enough into the individual amino acids necessary to make certain neurotransmitters and hormones.

Now aside form preparing you for sleep, melatonin also happens to be a powerful antioxidant, and protects against cancer.

A lot of studies have shown that melatonin interrupts the biochemical processes that tumors use to grow. It also keeps cancer cells from proliferating by causing the cells to commit suicide, along with cutting off its blood supply. In light of this, it makes sense why shift work is classified as carcinogenic, and why modulating your circadian rhythms and getting sleep is important for anyone dealing with cancer.

Melatonin also reduces oxidative stress, boosts the immune system, it’s anti-aging, helps eliminate certain types of migraines, may reduce age-related bone loss, protects against macular degeneration and glaucoma, it helps to modulate our energy production throughout the year as the seasons change based on the length of the day and night, and it makes the batteries of your cells – your mitochondria – more efficient.

Melatonin also happens to be involved in the body’s repair and regeneration programs – or what we call autophagy, which kick on only while you’re fast asleep.

The secretion of melatonin is the signal that turns those programs on. But here’s the thing: melatonin is released only after about four hours of complete darkness and is inhibited by blue light – the kind we use in lightbulbs and tech screens.

The production of melatonin is supposed to rise as the sun goes down to prepare you for sleep, with a surge that happens around 11 pm which acts as a signal for organ function to slow down and prepare for regeneration.

It peaks around midnight – 2 a.m. and then drops off to its lowest levels by about 4-5 a.m. So now imagine you go to bed around two in the morning and finally turn out all the lights.

Four hours later is when autophagy is supposed to kick on, only melatonin levels are virtually non-existent and cortisol production is now rising to wake you up, which means your repair and regeneration programs failed to turn on – and that’s a very bad thing…especially when you do it over and over every night.

So the thing to keep in mind here is that blue light at night suppresses melatonin. When you stare into a screen late at night, you’re essentially sending the signal to your body that the sun just came up and your melatonin levels drop and you screw up your circadian rhythm.


No doubt by now a lot of you are thinking “No problem, I’ll just supplement with melatonin and be good.”

Yeah, no. I mean, you can, but I don’t recommend it – despite the fact it’s relatively safe.

You see, melatonin is a hormone, and hormones have a lot of feedback loops involved with their production and levels – which in this case is dictated by your environment. When you go altering levels without correcting your environment and habits first, you run the risk of creating more trouble down the line.

My caveats here are if you’re over the age of 45-50, as melatonin levels wane as we age – hence why we see a lot of the problems I mentioned earlier, or if a person has vision problems or had their pineal gland removed, or is dealing with a serious health issue like cancer, then taking a small dose of pulsatile melatonin would be a good idea as long as their environment and habits were on point.

Pulsatile melatonin mimics healthy, natural melatonin levels which mimics healthy, normal circadian rhythms and restful sleep.

So how can we encourage our own melatonin production and entrain our circadian rhythm? Easy peasy.

Steps You Can Take

  • Start by getting morning sun on your eyes first thing every day. Make sure you don’t have anything between your eyes and the sun – no glasses, sunglasses, windows, or contact lenses. These things block the beneficial UV light needed to build ocular melatonin, release your hormones from your pituitary gland, and wind your body clocks.
  • Next, make sure to get at least 30 minutes of sun in the afternoon on your skin and eyes – again, for the same reasons.
  • Then as the sun goes down, you want to start blocking all blue light sources. Red light doesn’t affect melatonin production, so I recommend replacing light bulbs with amber bulbs, as well as wearing blue blocking glasses in the evening if you’re up late working or relaxing or watching TV. Download f.lux or iris for your computer to change the screen color temperature to red, and either use red screen film on your tablets and phone, or some of them have ways you can turn the screen red and eliminate the blue.
  • I also recommend trying to go to bed at a decent hour and stop staying up late mindlessly scrolling through social media, and make sure that your sleeping environment is absent any light that would impair melatonin production and release.
  • And finally, since earlier I mentioned that meal timing can help set circadian rhythms, I recommend eating breakfast in the morning and not eating anything late at night. This is the normal rhythm our bodies expect, as our digestive system shuts down at night to rest and repair.
  • Then wake up and repeat.

Okay, my friends – that does it for session two of The Sun Sessions. I look forward to seeing you again for session three. If you have any questions, please feel free to hit me up on Facebook. See you again soon!


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Jason Boyd

About our Guest

My name is Jason Boyd and I’ve spent over two decades nourishing and nurturing people from all over the world, in all stages of life, with all kinds of health issues.

My job is to assess where you’ve been, where you are now, and where you want to be, and then teach you how to provide yourself with the proper conditions you need to heal and be healthy. I help you coach up your adaptive physiology, engage your self-healing mechanisms, and restore balance and function back to your body by living in accordance with the laws of nature so that your evolutionary biology can thrive in our fast-paced modern world.

I created Bio+Logical Health & Nutrition out of a profound desire to help people live their best life. I’m not interested in diagnosing you or treating you for specific diseases, nor am I merely going to help you manage your symptoms.

My goal is to empower you with the knowledge you need to make the right decisions so you can enjoy the life you love with the people you love..

You’re not the disease you’ve been labeled with. You’re not the victim of bad genes.

You’re the creator of your best life.

It’s time you start living it.

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