Roger Seheult, MD
The Body Clock
Our daily habits of eating, sleeping, and outdoor sun exposure dramatically impact our health and well-being in profound ways scientists are just beginning to understand.
For most of human history, our ancestors got up with the rising of the sun. Many of their waking hours were spent outside, thus exposing them to bright light which provided numerous health benefits.
Modern life has eclipsed the need for working during daylight hours. Technology is at our fingertips day and night, and 24/7 restaurant service means meal time is anytime we feel like eating.
But there’s a serious downside to these conveniences. The health of billions on our planet is in jeopardy, and the solution is an about-face return to heaven’s plan for our well-being.
The human body is like a city.
A city is alive 24 hours a day. While many of its residents may sleep at night, city repairs continue to take place during the night hours, often unbeknownst to the residents. It is the same with our human bodies. Our bodies are capable of handling multiple functions throughout the day, but it is at nighttime when we get sleep that the body goes into restorative mode. During this time, the body and brain undergo cellular repair, removal of toxic waste, and release of molecules such as hormones and proteins — to name just a few processes. Without this restorative sleep, our bodies can get out of balance quickly, leading to long-term health consequences.
Our bodies have an internal clock that is called the circadian rhythm. Circadian in Latin means “around or approximately a day.” This is our sleep-wake pattern that occurs over the course of 24 hours in a day. It is triggered by light. God has given our bodies an internal regulator, but our human activities often derange this clock’s timing.
What do we do with light?
Prior to the invention of electricity, humans lived by the rising and setting of the sun. Going to sleep happened with the sun going down and awakening with the sunrise. Candlelight was the only means to stay awake for longer hours. It is known that sleep itself is dependent upon the secretion of melatonin from the pineal gland, a small gland in the center of the brain that receives information about the light-dark cycle from the environment. Scientists know that any light, but more so light in the blue-tinged part of the light spectrum, can suppress the production of melatonin from the pineal gland. This occurs via the suprachiasmatic nucleus (SCN), a small region of the brain in the hypothalamus that sits directly above the optic chiasm. When light, but especially blue light is encountered by the eye, it sends signals through the SCN to the pineal gland that can lead to delays in the nighttime circadian rhythm. If this pattern continues habitually, the circadian rhythm can become significantly delayed.
Society today is experiencing significant disruptions to circadian rhythms. Surveys regarding sleep show that over 60% of respondents worldwide report some type of sleep disturbance on a nightly basis. In the US, 50-70 million or more people are affected by a sleep disorder. So why is this happening now?
Our modern culture allows us to work at all hours of the day and night. With the advent of electricity, there is little that is physically stopping us from work. When we get home, we get on the internet, watch television, entertain ourselves, and finish our work online. Over the last 20 years, screens have become increasingly involved in all of these activities. The common theme with the increased screen time is that computers, laptop screens, televisions, cell phones, and tablets all use LED technology that can emit high amounts of light. As the sun goes down, the lack of visible light normally prompts our body through the SCN and pineal gland to release melatonin. Attempts at using blue-light-blocking glasses have not been found to truly resolve sleep cycle disruptions despite the fact that blue light is more effective at suppressing melatonin. The reality is that any kind of light can impact our circadian cycle. Light is so powerful that it penetrates the eyelids, and even ambient lighting at night can inhibit the secretion of melatonin.
Interestingly, Ellen G. White provides wise counsel on this topic. She says, “I know from the testimonies given me from time to time for brain workers, that sleep is worth far more before than after midnight. Two hours’ good sleep before twelve o’clock is worth more than four hours after twelve o’clock. . . .” (Ellen G. White, Manuscript Releases, vol. 7, p. 224).
While light is detrimental to the human body in the late evening, the opposite is true in the morning.
Studies show convincingly that exposure to early morning light — either by opening the shades on the windows or by exposure to a gradually illuminating lightbox — actually anchors circadian rhythm, improves mood, and improves cognition.
Light intensity is measured via a standardized unit called lux. When an individual is outside on a sunny day, he or she can be exposed to about 100,000 lux. In order to get your circadian rhythm started you need 10,000 lux for 20 minutes. By comparison, the typical indoor light may only be around 50 lux, and thus people who only stay indoors may not get enough light to reset the circadian rhythm. Outdoor light is much stronger than indoor light, and ironically whereas blue light at night is considered detrimental, it is considered beneficial to get exposed to it during the day.
Although we know there are different types of wavelengths on the light spectrum, we are just now learning how important these different wavelengths are. As we move above the visible light spectrum into the ultraviolet wavelengths, we know that UVB light helps to produce vitamin D in our skin, especially between the hours of 10 a.m. and 2 p.m.
Conversely, beyond the lower end of the visible light spectrum is the infrared light spectrum. This infrared radiation is emitted proportionally throughout the day. Scientists have proposed that infrared radiation is capable of penetrating through our clothes and skin directly into our cells to stimulate the machinery in the mitochondria, the powerhouses of the cell, to produce melatonin. Yes, this is the same melatonin made by the pineal gland, but in orders of magnitude higher quantity. Melatonin is not only a sleep hormone but it is also a powerful antioxidant. Like internal combustion engines generating heat while running, mitochondria generate hydroxyl radicals, which are extremely reactive oxygen compounds that can damage nearby proteins in the cell. When these hydroxyl radicals are created, melatonin is used to degrade them. Melatonin is actually the most powerful of all antioxidants. It also can ramp up other antioxidant systems like glutathione. When the mitochondria are not able to degrade hydroxyl radicals, they can become dysfunctional. Many chronic diseases such as diabetes, dementia, and learning disabilities such as autism have been associated with dysfunction of the mitochondria.
What about melatonin supplements?
The supplement industry is largely unregulated. There is no company or government agency that verifies that what is stated on the label of a supplement is actually what you are getting. There are, however, reputable drug companies that will use an independent third-party laboratory to verify a supplement. It is highly encouraged that people research the company from which they are buying supplements.
If you do decide to take a melatonin supplement, you need to take an appropriate dose. It is recommended that you should take no more than 1-3 mg in the evening before retiring. If you take high doses at night, e.g. up to 10 mg, this could lead to worse sleep than without the supplement; if you take it during the day it could disrupt the whole circadian rhythm. Furthermore, oral supplements of melatonin are not capable of getting into the mitochondrial machinery to deal with the hydroxyl radicals and as such are of little benefit.
The best way to get melatonin and light therapy is to get outside and get sunlight exposure. It does not even have to be direct sunlight exposure as you can still reap the benefits of infrared radiation. Grass, trees, and plants are natural reflectors of near-infrared radiation. When in the sun, near-infrared radiation will be felt as warmth, much like a campfire which also generates infrared radiation. Unfortunately, due to new building codes and energy-efficient windows, the likelihood of getting adequate exposure to infrared light inside a building is extremely small. Furthermore, as Americans, we only spend about 7% of our waking hours outside.
What can you do to mitigate light exposure in the evening? Lights in the evening should be kept dim and screen time should be minimized as it gets closer to your sleep time. Switching from using overhead ceiling lighting to lights such as incandescent lamps that will be seen by your eyes in the lower visual field may also be useful. Bedrooms should not have any night lights as these again can penetrate the eyelid and disrupt the sleep cycle.
In addition to light, there is another factor that can influence our circadian rhythm called time-restricted eating.
What is time-restricted eating?
Also known as intermittent fasting, time-restricted eating limits the hours a person can eat during the day. It is not about restricting caloric intake.
Intermittent fasting enables the body to switch from building (its daytime job) to repairing (its nighttime job). In order for the body to go into repair mode it must be in a fasted state, which occurs 4-6 hours after the last meal. In a fasted state, the body uses up its excess circulating glucose stores and then switches to a metabolic state utilizing ketones instead. Ketones signal the body to switch into repair mode and allow the body’s “construction crew” to come out.
The metabolic effects of digestion far outlast the last meal ingested, so it is important to coordinate the fasting state with the sleeping state. As in a city, road repair is easier to maintain when there is no traffic. This allows the maximal effect of fasting to be realized.
Another important point to note is the body clock’s effect on metabolism. A calorie in the morning is not the same as a calorie in the evening. Circadian rhythm studies show that the body is more sensitive to insulin in the morning than in the evening, meaning that less insulin is needed in the early hours. This translates into better metabolic health. For this reason it is important to limit the time that we are eating in a 24-hour day so that the time our body has for repair is expanded. Biologically it appears that the best time to take in calories is earlier in the day.
When I first switched to intermittent fasting I decided to skip breakfast and eat only lunch and supper. Many people are doing this thinking they are getting the benefits of time-restricted eating. But on this plan I lost no weight. After a one-month trial I switched to eating breakfast and lunch only and noticed a difference.
A recent study out of China with 120 subjects restricted their eating to ten hours a day. They ate only between 8 a.m. and 4 p.m. They weren’t told what or how much to eat – the only restriction was the time allotted for eating. The results were that the HbA1c, a measurement of diabetes, dropped 20% in the intervention group (versus 8% in the control).
Seventh-day Adventists have known for more than a century that eating two meals a day (starting with breakfast) is the optimal dietary plan for most people. Today scientific research validates this principle.
Many aspects of our modern culture work against the natural circadian rhythm of our internal body clocks.
While God grants us freedom of choice, He does not give us freedom from the consequences of our choices. Our bodies have not changed. When we live contrary to God’s plan and design for our health, we suffer because of it. But when we yield ourselves to Him and live according to nature’s laws, we are blessed.
“If you diligently heed the voice of the Lord your God and do what is right in His sight, give heart to His commandments and keep all His statutes, I will put none of the diseases on you which I have brought on the Egyptians. For I am the Lord who heals you” (Exodus 15:26).
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