Biohacking our Circadian Rhythm for better health
BEHOLD THE POWER OF THE SUN
When I tell my clients to get out in the morning and look at the sunlight for at least a few minutes (ideally 15), within an hour of waking - cloudy or sunny, and even right before sunrise, I often get a lukewarm reaction, and get the distinct feeling they yes me just to humor me. I can almost hear them think: “here’s another pseudo-science evangelist - how in the name of God is looking at the sun going to help me lose weight? If that were true, don’t you think everyone would be doing that?” Well, that would be the idea. A few minutes of sun exposure in the morning help sync the innate ability of the body and mind to align with cyclical changes in the environment, by fine-tuning our inner clock. In my observation, professionals in the healthcare industry, both those trained in the conventional model and those on the functional side of the field, place little to no emphasis on regulating this function in the treatment of metabolic ailments - and for that matter, any health dysfunction. Without taking a deep dive into human biology, let’s explore this fundamental ability of our neuroanatomy.
THE CIRCADIAN RHYTHM
[The fist scientific observations of the circadian rhythm date back to the 18th century. In the ‘60s, a neurological mechanism was identified that regulates our 24hr sleep/wake cycle, and more studies were conducted throughout the ‘80s that determined the relevance of specialized genes involved in this eco-biological cycle. In 2017, a Nobel Prize was awarded jointly to scientists Jeffrey C. Hall, Michael Rosbash and Michael W. Young for their discoveries of molecular mechanisms that control the so-called Circadian Rhythm. These discoveries hold important clues for biohacking our way to better health.]
Imagine what it would be like if you and everyone around you would randomly decide it’s time to call it a day, stop everything and go to sleep, or if someone invited you for dinner at 9am, or if the school your children go to had 2 am to 6 am classes. Thankfully, as a species, we all display parallel and compatible social behaviors at the same times of day, within the same geographical and social context. Our body is evolutionarily programmed to function around a naturally recurring 24-hour sleep/wake cycle, known as the circadian rhythm, that regulates neuroendocrine functions such as food intake, sleep patterns, core temperatures, metabolism, pain tolerance thresholds, psychomotor performance, and innate defense mechanisms, along with many other behaviors. Even more remarkably, different systems in our body activate at different times, but in a fixed pattern. For instance, the adrenal glands pump cortisol with the highest pulse intensity in the 15 to 30 minutes after we wake up, to quickly rouse us for diurnal activities; that pulse also sets off a timer of 16 HOURS, during which cortisol progressively dwindles down. In the evening, the pineal gland releases melatonin, which gradually nudges us into a sleepy state as levels of excitatory hormones drop.
Also in a timely fashion, our immune cells migrate into tissues during the day, but linger in our lymph nodes at night, where they make a memory of the offenders they had to fight off throughout the day (so the system is better prepared for future assaults). Specific circadian times have been linked with the onset of acute diseases, particularly in the cardiovascular system. For instance, most heart attacks happen during the last phase of sleep or in the first 3 waking hours; this is because some functions in the first hours of the day require more myocardial oxygen support, but as biology would have it, when we wake up, platelets are particularly adhesive to the vessels, hence the blood is more prone to clotting. Moreover, the enzymes that normally break down clots are least active in the early hours, further contributing to a reduction of coronary blood flow. Our digestive organs also happen to have a preferred schedule, as they work more efficiently during the daytime, though the liver likes to make cholesterol while we sleep. But perhaps the most outward and tangible manifestation of these spot-on, around-the-clock recurrences is men’s beard: men have a 5 o’clock pm ‘shadow’, but no shadow shows up at 5 am, indicating a biologically scheduled facial hair growth. But how do these systems know when to do what, and why?
THE SUPRACHIASMATIC NUCLEI & THE CLOCK GENES
The body knows what time it is by way of a subconscious response to the rising and setting of the sun. Inside a specific region of the brain called the hypothalamus, that connects the nervous system with the endocrine system, lies a cluster of about 20,000 neurons, collectively named ‘suprachiasmatic nuclei’- SCN for short. Located right above the intersection of the two optical nerves, the SCN receives a nudge in the form of a nerve impulse that comes through the photosensitive ganglion cells in the retina. The eye nerve impulse is sparked by visual perception of a specific wavelength of light, the one created by low solar angle (when the sun is low in the sky, at rising and setting); upon this nudge by the optic nerves, the hypothalamus secretes several chemicals into the body that organize and properly time organismic processes. In short: the eyes capture the low rays of the sun, and tell the brain to set things in motion for the entire body, in a tightly regulated sequence, for all phases of that particular day. Interestingly, research has found that visually impaired people still have the ability of capturing light/dark transitions, since perception of this wavelength is independent of sightedness.
However, though the brain houses our ‘circadian rhythm central’, from which neuro-hormonal signals travel all throughout the body to synchronize all 30+ trillion cells to the day-night cycle, scientists have discovered that individual cells in different organs are equipped with their own little clock, which is regulated by specific genes that code for ‘clock proteins’: one (named PER gene) sets the clock for 23 hours, the other one (named CLK gene), programs for a 30 hour run. Thes two genes keep each other at bay, so to speak, in a feedback loop, and their daily interactions orchestrate clock protein level fluctuations inside the cells, influencing cell activity, ensuring enzymes are manufactured, blood pressure is under control, cells are dividing, detoxification is taking place, neurotransmitters are being produced, etc. While influenced by both external and internal environmental cues, all local clocks are synced to ‘big central’, the main SCN pacemaker. This compliance to higher management is of crucial importance since different organ cells don’t need to be active at the same time, but rather work in shifts like factory workers, each department contributing to global production. In fact, it is the natural sunlight that synchronizes the body to a perfect 24-hour cycle, but other cues also contribute to regulating the circadian rhythm, namely meal times, social interactions and temperatures.
It’s easy to see how our health and wellbeing are directly affected when there is a misalliance between our external environment and our inner biological clock. Most of us are familiar with the unsettling cluster of symptoms of ‘jet lag’, a disruption in the normal order of sleeping, eating and all related functions that we experience when we travel across different time zones, caused by such misalignments. Frequent and uncontrolled disorders in our lifestyle that trigger functional setbacks are associated with an increased risk for various diseases: such is the case of ‘social jet lag’, a term that refers to late night outing, eating and drinking for the purpose of socializing, that cause disarray in our biological recurrences.
But by now you’re probably wondering: how exactly does all of this specifically relate to fat loss?
THE CIRCADIAN RHYTHM OF FAT CELLS & TIME RESTRICTED EATING
Biohacking the circadian rhythm to a precise 24 hour cycle has significant metabolic benefits. The word circadian itself, which comes from the Latin circa, meaning approximate, and diem, which means day, indicates that while the body has a daily rhythm, in the absence of environmental cues and information such as time and food availability, its self-regulatory mechanism dos not run on an exact 24 hour loop, and demonstrably shifts out of the solar day in the absence of adequate light exposure.
As I stated earlier, though circadian rhythm genes specific to different tissues are under governance by the hypothalamic central clock, to an extent they locally control the behaviors of their own tissues. This holds true for adipose (fat) cells, or adipocytes, as well. Because energy is stored as fat, and adipose tissue is an endocrine organ (it produces leptin, adiponectin, steroids and other hormones), adipocytes (fat cells) play a crucial role in energy balance. Scientists conducted an experiment on two groups of mice, by removing, in one of the groups, a genetic protein in adipocytes that controls rodents’ circadian rhythm. They fed all the mice the same diet and kept their activity level the same, and at the end compared their weight. The mice with no genetic circadian protein gained 50% more fat than the intact mice, as they were eating the same foods but at times of the day their particular metabolic biology does not efficiently support. Observation studies have been conducted in humans on late shift workers, and concluded that nightshifters tend to have higher rates of obesity and metabolic disease. In essence, eating at inappropriate times, or times that are not in sync with human circadian rhythms, disrupts metabolism, irrespective of type of diet. Scientists have discovered that eating at a time that does not line up with our central clock will cause adipose tissue to store instead of spending energy, shifting the energy balance towards fat accumulation and obesity.
Adjusting our circadian rhythm to the solar day cycle has weight loss benefits in several inteconnected ways. At the cellular level, this regulation provides fat cells with cues that inform proper energy usage and storage. From a hormonal standpoint, regulating cortisol levels throughout the day, ensuring it is highest in the morning and lowest at night, benefits weight management at least two-fold: for one, normal cortisol levels during the day have an anti-inflammatory effect in the cells, whereas high cortisol, particularly at night, is pro-inflammatory. High night-time cortisol worsens insulin resistance and disrupts sleep, which translates into both blood sugar disregulation during the night, and appetite disregulation the next day. Secondly, thyroid function and circadian rhythmicity are interconnected: disruptions in sleep and cortisol fluctuations impact the hypothalamic-pituitary-thyroid axis and TSH secretion. Hypothyroidism makes the receptors on fat cells more sensitive to insulin, causing them to grow in size. A disrupted circadian rhythm impacts neurotransmitters such as GABA, serotonin, glutamate and dopamine, which may lead to depression and overeating. Research has shown that 2 days of early light exposure can adjust the cortisol/melatonin rhythm, hence the secretion of other neurotransmitters, for one week. This is because sunlight has an effect on the circadian clock, as explained earlier in this article, that is independent of conscious vision. Likewise, avoding bright light exposure or reducing it to a minimum in the last couple of hours before going to bed has been repeatedly shown by research to have a regulatory effect on circadian rhythm, sleep quality and biological functions at large. It is wrongfully assumed that only blue light disrupts sleep, while in truth all kinds of light impact melatonin production.
It is worth noting that while light is the dominant synchronizer of the circadian rhythm, sleep hygiene and feeding times have a profound impact on regulating cellular functions. Dr Satchin Panda, a Professor of Regulatory Biology at the SALK Research Institute in California, has been successfully conducting research showing that restricting the feeding window to 8-10 hours per day improves all metabolic conditions by regulating circadian rhythmicity.
THE CIRCADIAN RHYTHM & AGING
Older individuals display increasingly different sleeping habits than younger ones, with earlier bedtimes and a reduction of nonREM, slow wave sleep, the deeper stages of sleep, with more frequent awakenings. These changes are also seen in middle-aged, healthy individuals. Several studies have shown that the human circadian period, which normally runs on a longer cycle than the 24 hr environmental period (as previously mentioned in this article) undergoes a reduction in amplitude with normal aging - beginning approximately at mid-life - and actual shifts in phases are seen in aging individuals. Scientists still don’t know for sure what causes these disruptions, but most studies point to a combination of faulty expression of the CRY and PER clock genes and a lesser sensitivity/response by the SCN to environmental cues. This translates into a decreased production of melatonin, and an altered distinction between sleep and wake cycles. There is strong evidence that aging eyes may be less efficient at capturing short-wave morning light, as proven by the fact that cataract surgery seems to improve sleep patterns.
Mice experiments have shown that a mismatched internal clock leads to rapid aging, sarcopenia (loss of muscle mass), cataracts and impaired hair growth. Manipulating environmental cues to regulate the circadian rhythm has then been shown to have a positive effect on their genetic expression and extend their life span, whereas a perurbation of circadian genes in peripheral tissues is associated with metabolic disorders, hence rapid aging. Mice with precise 24 hr circadian rhythms have been found to live 20% longer than the mice with shorter or longer periods.
In conclusion: the more circadian regolatory cues we give our brain and body throughout the day, the more efficient our cellular regulation will be, to the benefit of our emotional well-being, weight management, and healthy aging.
Sources:
https://www.sciencedirect.com/science/article/abs/pii/S014976342100347X
https://www.nobelprize.org/prizes/medicine/2017/advanced-information/
https://www.ncbi.nlm.nih.gov/books/NBK546664/
https://www.ncbi.nlm.nih.gov/books/NBK546664/