Every day, we’re faced with a monumental threat to our health. Constantly, we’re all overexposed to light, and we don’t even realize that this is a hazard to our wellbeing.

Evolution has programmed almost every living thing on planet earth to function and operate according to a circadian rhythm, even plants and bacteria. The circadian rhythm serves as the most fundamental component in physiology, allowing an organism to regulate all biological processes and optimize its ability to survive. Most people understand a circadian rhythm to be the body’s internal clock that functions on a 24-hour sleep/wake cycle based on the rise and fall of the sun each day. While this is true, there are new and harmful variables that we need to start taking into account.

Ever since electric lights were invented, most of us have become largely dependent on them. Now, we’re able to stay awake as late into the night as we want, which completely prevents our circadian rhythm from being able to function properly, let alone optimally.

However, that’s nothing in comparison to the compounded complications brought on by the almost non-stop usage of computers, phones, and other digital interfaces in recent years. This puts us at a strange point in human history where people are spending more time inside than ever before, leaving us deficient in sunlight and vitamin D, yet simultaneously overexposed to artificial light during the nights.

From sunlight deficiency to darkness deficiency

Human physiology was never designed for light exposure after dark, especially not the type of light emitted from our electronic devices, known as blue light. Over billions of years, life on Earth has been cycling through the 24-hour circadian rhythm of bright daytime light, which shines at a high intensity anywhere between 10,000 and 100,000 lux, and an absence of light at night, which shines at a very low intensity between 0.0001 and 0.5 lux [1]. 

Circadian rhythm, in its most accurate sense, can be thought of as a grand symphony of biological functions, all of which are able to operate in perfect synergy with each other, and just like any symphony, we need a composer to coordinate all the moving parts harmoniously. Hormones released by the endocrine system’s collection of glands act as the composer, and they are responsible for controlling nearly every single biological activity in the human body [2].

Just as the success of any particular section in a symphony is largely contingent on the success of the other sections, the same is true in the circadian rhythm. Once one hormone becomes dysregulated, so too will many other hormones, leading to an overall poorly functioning circadian rhythm. With that said, excessive exposure to artificial light at night is one of the most prevalent and significant hormone disruptors in our everyday lives. 

This problem is often overlooked due to society’s acceptance of doing more, working longer, and being reachable through digital interfaces as much as possible. At the same time, a massive increase in light pollution and urbanization over the past hundred years has resulted in a major loss of nighttime darkness [3]. Although these things may make our lives easier, everything has a cost. As a result of this artificial light toxicity and darkness deficiency, there is a widespread derangement in circadian rhythm running rampant throughout the population. Night shift workers are a particular group of people who consistently suffer the largest derangements in their circadian rhythms, which subsequently puts them at a greater risk of cardiometabolic disorders [4] and breast cancer [5]. This correlation indicates that as our circadian rhythm becomes increasingly dysregulated, we actively put ourselves at an increased risk for developing severe and chronic illnesses. 

Darkness deficiency leads to melatonin deficiency

Even though melatonin has always been associated with sleep, its more accurate designation is the “hormone of darkness” [6]. When the photoreceptors in the eye’s retina detect the absence of light, a signal is sent to a cluster of 20,000 nerve cells within the brain’s hypothalamus called the suprachiasmatic nucleus (SCN), which then stimulates the pineal gland to start ramping up melatonin production for the night [1]. At this point in our hormonal symphony, an important shift is beginning to take place. As the melatonin makes its way through our circulatory system to achieve its primary function of inducing tiredness, it also serves a secondary purpose. In order to optimize overall health, melatonin signals to all the other glands in the endocrine system that it’s also time to shift their hormone production in preparation of sleep.

With this is mind, it’s very important to note that even subtle changes in light before bedtime can seriously alter melatonin synthesis [8]. Late night exposure to light at higher intensities around 200 lux can suppresses pre-sleep levels of melatonin by up to 70%, but even exposure to very dim light with intensities under 3 lux can suppresses melatonin synthesis by as much as 12.5% [8]. Additionally, although all light has the potential to reduce melatonin production, certain types of light can be worse than others. Melatonin production is most sensitive to short-wavelength (blue) light, which is why light from computers and other electronic devices is particularly problematic. As a consequence of the havoc that blue light can wreak on our circadian rhythm and hormonal symphony, we drastically increase our risk of acquiring dangerous illnesses, such as cancer [9].

The vital correlation between melatonin and vitamin D

During the COVID-19 pandemic, there grew a heightened awareness of the global vitamin D deficiency because of its detrimental impact to immune health. When researchers and medical doctors began looking deeper into the root causes of the population’s vitamin D deficiency, it “came to light” that this is largely due to people not getting enough direct sunlight on a daily basis [10]. By lacking enough exposure to sunlight, people are not able to access the essential ultraviolet light spectrum that is required to convert the vitamin D precursor, which lies within the skin, into the active form of vitamin D. 

Just as a sunlight deficiency will inevitably lead to a vitamin D deficiency, it is equally assured that a darkness deficiency will lead to a melatonin deficiency. In our published review article [6], we brought up the thought-provoking question of whether melatonin could be the “next vitamin D,” due to this similar set of circumstances. We pushed the conversation further to say that there is a similarly pervasive “darkness deficiency” causing widespread lowered melatonin levels. 

Another scientific paper discussed how melatonin and vitamin D are “two sides of the same coin.” This is especially true when it comes to diseases, such as multiple sclerosis, that are more common in regions at northern latitudes. Researchers have shown that this is due to the high degree of darkness and negligible amount of light in these locations [11]. 

The takeaway here is that there is balance to be struck between sunlight and darkness. Light and darkness are constantly working together, but simultaneously opposing each other, exactly like the synergistic harmony of yin-yang. It is precisely in this way that our hormonal symphony is able to flourish. 

How do you know if you have darkness deficiency?

When it comes to being deficient in darkness, and subsequently lacking adequate melatonin production, no one is exempt. Living in a well-lit urban area, working on a computer before bed, and staying up late into the night staring at a television or phone are all a few of the many aggravating variables that can harm our sleep, and thus our long-term cognitive, emotional, and physical health. 

Here are some subtle signs that might suggest you have darkness deficiency:

• Being on the computer, iPad, television, or other electronic devices after 7 PM without having any blue-light blocking filter activated.

• Using a smartphone or another electronic device while in bed before going to sleep, even with a blue-light blocking filter activated.

• Reading books in bed before going to sleep.

• Keeping lights on in the bedroom when sleeping, even if it’s just a night light, LED alarm clock, or the light creeping through the blinds and curtain of your window from outside.

• Spending time in well-lit areas like a gym, shopping mall, or sporting events after 7 PM.

Health issues related to low melatonin

Most people think of melatonin as merely a hormone, but it’s also much more than that --- it’s a potent anti-inflammatory, antioxidant, and free radical scavenger [6]. Best of all, melatonin is a powerful brainwashing tool…but not the type of brainwashing you’re probably thinking of. We mean that melatonin, quite literally, helps clean out waste and toxins from the brain that would otherwise accumulate and cause harm later down the line. Incredibly, emerging research is showing that the brain’s glymphatic system is able to take advantage of the melatonin secreted into our cerebrospinal fluid (CSF), and then use it to flush out amyloid-β peptides (Aβ) [12]. 

And why is this important?

This is extremely exciting to learn, because Aβ peptides collecting into plaque deposits within the brain constitutes 1 of only 2 established pathologies required to diagnose Alzheimer’s disease (AD) [13]. Now, knowing that melatonin can flush out Aβ peptides before they form into dangerous plaques, researchers have investigated how melatonin can impact the progression of Alzheimer’s disease. Using animal models of AD, melatonin supplementation has been shown to defer “Aβ accumulation, enhance its clearance from the CNS, and prolong animal survival” [12]. 

In addition to protecting against neurodegenerative diseases, melatonin is responsible for removing many other forms of cellular waste from the brain, such as dying cells [12]. Melatonin also improves the overall function of mitochondria across the entire human body [14]. Taken all together, without sufficient melatonin production, there are strong associations with cognitive decline and diminished quality of our immune-inflammatory response, thus putting ourselves at greater risk for health complications like dementia, autoimmune disease, infertility, and cardiometabolic syndrome [6].

How Daylight-Saving Time is aggravating our darkness deficiency

At this point, it’s probably very evident that melatonin plays a huge role in our health on a chronic scale, but the same can be said for melatonin’s importance on an acute scale.  

The sudden one-hour time change at the beginning of Daylight-Saving Time (DST) holds the potential to cause a very detrimental ripple effect that will severely harm multiple facets of life. All because of how the daily balance of light and dark is altered.

There’s a strange phenomenon where, during the week following DST’s “spring forward” time change, the population experiences a significantly increased mortality rate. Several studies observed that cardiovascular events, such as heart attacks, increased by up to 29% on the Monday immediately after the DST change [15]. There is also an 8% increase in stroke rates during the Monday and Tuesday after the DST change [16]. All in all, autopsy data show a significant increase in TOTAL deaths over the entire week following the change. This is including non-natural deaths, such as traffic collisions and suicide, in addition to natural deaths, such as cardiac insufficiency, heart attacks, and strokes. 

Another study concluded that DST’s (seemingly mere) one-hour time change has several long-lasting, chronic impacts on population health, including complications due to pregnancy, childbirth, noninfective enteritis and colitis, and circulatory diseases [17].

Plus, if that weren’t enough, melatonin levels drastically and continually decline with age [6]. By the time we reach our fifties, sixties, and beyond, the risks for several chronic diseases are more prevalent than ever, especially for dementia and neurologic decline. Researchers are collecting data that strongly correlate the rise in chronic disease as we age with our naturally diminishing melatonin levels over the course of our lives [12]. 

What can you do about darkness deficiency?

Now imagine that someone who is excessively exposed to artificial light at night, is chronically stressed from long hours of work, and is well into their adulthood --- already, they’ve stacked the deck in favor of aging poorly and increasing their risk of developing chronic diseases. The circadian rhythm essentially serves as the foundation to our body’s overarching health. Once the foundation starts to falter, everything else will crumble in response, especially our ability to live a long and healthy life.

Here are some strategies to help fight off darkness deficiency:

1.     Aim for darkness at night: Reduce or avoid artificial, short-wave, blue light at night by using blue light blocking filters on devices, dimmers on lights, and also dimming the brightness intensity on device screens for at least 2-3 hours before bed. 

2.     Choose red light over blue at night: Opt for red-light sources in the evening to offset exposure to blue light, such as using red-light light bulbs, salt lamps, candles, red-tinted eyeglasses, and even fire in the fireplace.

3.     Expose the eyes to blue light in the morning: Blue light is not entirely undesirable – it simply has to be timed with the rhythm of the day, which is most optimal in the morning. Bright light therapy early in the day has also been used for reducing symptoms of seasonal affective disorder and even recalibrating circadian rhythm [1]. 

4.     Wear blue-light blocking eyeglasses at night: If technology is unavoidable, wear blue-light blocking glasses when working on the computer or even using the phone.

5.     Make your bedroom “light-proof”: Keep your bedroom as dark as possible by removing nightlights and bright LED lights (e.g., alarm clocks), and by hanging blackout curtains. If you want to go the extra mile, you could even opt for wearing an eye mask to shield light during slumber. 

6.     Be one with the darkness: Align yourself with nature by winding down at night as it becomes darker outside. Alter this rhythm with the seasonal shifts. 

7.     Limit food intake at night: Since food intake and appetite is controlled by hormones, and therefore circadian rhythm, reducing changes to metabolic signals at night will significantly help keep glucose and insulin in check, as well as cardiometabolic disease risk low. Of note, it is always best to work with a health professional that can personalize the timing of your food intake to your needs. 

8.     Replenish lost or declining levels of melatonin with a high-quality melatonin supplement:Herbatonin®, our plant melatonin made from alfalfa, chlorella, and rice, has been shown to outperform synthetic melatonin by 646% in anti-inflammatory activity, up to 470% greater inhibition in free radical scavenging, and is up to 100% higher in antioxidant potential, giving your body exactly what it needs when you are lacking in what the darkness provides [18]. Plus, we should certainly never overlook how research has been able to show that melatonin supplementation is capable of warding off Alzheimer’s and dementia, and is also involved in the renewal of the brain’s neural stem cells during sleep. 

Sources Cited

1. Meléndez-Fernández, O.H., J.A. Liu, and R.J. Nelson, Circadian Rhythms Disrupted by Light at Night and Mistimed Food Intake Alter Hormonal Rhythms and Metabolism. Int J Mol Sci, 2023. 24(4).

2. https://my.clevelandclinic.org/health/articles/21201-endocrine-system

3. Ouyang, J.Q., S. Davies, and D. Dominoni, Hormonally mediated effects of artificial light at night on behavior and fitness: linking endocrine mechanisms with function. J Exp Biol, 2018. 221(Pt 6).

4. Ansu Baidoo, V. and K.L. Knutson, Associations between circadian disruption and cardiometabolic disease risk: A review. Obesity (Silver Spring), 2023. 31(3): p. 615-624.

5. Wei, F., W. Chen, and X. Lin, Night-shift work, breast cancer incidence, and all-cause mortality: an updated meta-analysis of prospective cohort studies. Sleep Breath, 2022. 26(4): p. 1509-1526.

6. Minich, D.M., et al., Is Melatonin the "Next Vitamin D"?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements. Nutrients, 2022. 14(19).

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8. Gooley, J.J., et al., Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. J Clin Endocrinol Metab, 2011. 96(3): p. E463-72.

9. Haim, A. and A.E. Zubidat, Artificial light at night: melatonin as a mediator between the environment and epigenome. Philos Trans R Soc Lond B Biol Sci, 2015. 370(1667).

10. Sharun, K., R. Tiwari, and K. Dhama, COVID-19 and sunlight: Impact on SARS-CoV-2 transmissibility, morbidity, and mortality. Ann Med Surg (Lond), 2021. 66: p. 102419.

11. Ghareghani, M., K. Zibara, and S. Rivest, Melatonin and vitamin D, two sides of the same coin, better to land on its edge to improve multiple sclerosis. Proc Natl Acad Sci U S A, 2023. 120(14): p. e2219334120.

12. Reiter, R.J., et al., Brain washing and neural health: role of age, sleep, and the cerebrospinal fluid melatonin rhythm. Cell Mol Life Sci, 2023. 80(4): p. 88.

13. Murphy MP, LeVine H 3rd. Alzheimer's disease and the amyloid-beta peptide. J Alzheimers Dis. 2010;19(1):311-23.

14. Tan DX, Manchester LC, Qin L, Reiter RJ. Melatonin: A Mitochondrial Targeting Molecule Involving Mitochondrial Protection and Dynamics. Int J Mol Sci. 2016 Dec 16;17(12):2124.

15. Manfredini R, Fabbian F, De Giorgi A, Zucchi B, Cappadona R, Signani F, Katsiki N, Mikhailidis DP. Daylight saving time and myocardial infarction: should we be worried? A review of the evidence. Eur Rev Med Pharmacol Sci. 2018 Feb;22(3):750-755.

16. https://www.aan.com/PressRoom/Home/PressRelease/1440

17. Zhang H, Dahlén T, Khan A, Edgren G, Rzhetsky A. Measurable health effects associated with the daylight saving time shift. PLoS Comput Biol. 2020 Jun 8;16(6):e1007927. 

18. Kukula-Koch, W., et al., Is Phytomelatonin Complex Better Than Synthetic Melatonin? The Assessment of the Antiradical and Anti-Inflammatory Properties. Molecules, 2021. 26(19).