Light: The Forgotten Spectrum

Light is a fundamental environmental element that is needed for a biology and the day/night cycle plays an important biological functions and processes. Light may be how our hormones, metabolism and circulatory systems operate, yet, excess light at a particular wavelength can potentially have adverse health effects such as low Vitamin D, low melatonin, increase in diseases and even potentially loss of eye sight. The abundance of LED lighting has increased with a 30% year on year growth with predicted saturation of 75% across all lighting areas by 2020, it will mean that we will live in a blue-light toxic environment that will likely be the single most toxic non-native EMF (nnEMF) of this century (Goldman Sachs International, 2016).

Keywords: blue light, red light, UVA, UVB, LED, incandescent, vitamin D, 25OHD, PIP2, lipofuscin

According to the National Human Activity Pattern Survey (NHAPS), we spend 86.9% of our time indoors (Klepeis et al., 2001).  This is the science that has been generalized by many others to indicate that humanity spends up to 90% of their time indoors. According to the National Human Activity Pattern Survey (NHAPS), we spend 86.9% of our time indoors (Klepeis et al., 2001).  This is the science that has been generalized by many others to indicate that humanity spends up to 90% of their time indoors.

UV light hitting the earth’s surface is primarily UVA and UVB, while UVC is blocked by our atmosphere, yet UVB light is only available when the sun reaches 35 degrees above the horizon since much of the earth’s atmosphere blocks UVB until this angle is reached (Chen et al., 2007; DMinder, 2018; WHO, 2018). The latitude and altitude also affects UVB, so depending on the location on earth (ie latitude), the time when UVB would be available can be limited to specific times, while for every 1000m increase in altitude, the UV levels increase by approximately 12% (DMinder, 2018; WHO, 2018).  Therefore, during daylight hours, it is primarily composed of UVA and IR radiation. Infrared (IR) light penetrates the skin several millimetres (IRA,IRB), and this is typically the heating effect that we feel on our skin, while IRC is only superficial penetration on the outer surface of the skin (ICNIRP, 2013).

Sunlight from sunrise to sunset has a spectral and colour distribution that changes throughout the day with various intensity (as depicted below). 
As newly built buildings become energy efficient, and electricity costs sky rocket, the power revolution has shifted towards the efficiency of devices in the home and renewable energy options. A particular focus area these days, is the energy efficiency of lighting within the home and office. From the original invention of the Edison bulb in 1882, artificial light has allowed our night time existence to be extended beyond sunset (WikiPedia, 2018b).  Incandescent light bulbs were developed for commercialization in 1878 by Joseph Swan and the compact fluorescent bulb was invented in 1976, this eventually led to the development of the LED light bulb (WikiPedia, 2018c, 2018a, 2018d). Yet, not all light is equal. The artificial light generated from these bulbs are specific to particular wavelengths of light, and also by colour. 
The visible light spectrum is part of the electromagnetic spectrum, ranging from 400nm to 700nm, with ultraviolet light (UVA, UVB, UVC) covering 100nm to 400nm and infrared light (IR-A, IR-B, IR-C) from 700nm to 1mm range (ICNIRP, 2013; WHO, 2018). UV light hitting the earth’s surface is primarily UVA and UVB, while UVC is blocked by our atmosphere, yet UVB light is only available when the sun reaches 35 degrees above the horizon since much of the earth’s atmosphere blocks UVB until this angle is reached (Chen et al., 2007; DMinder, 2018; WHO, 2018). The latitude and altitude also affects UVB, so depending on the location on earth (ie latitude), the time when UVB would be available can be limited to specific times, while for every 1000m increase in altitude, the UV levels increase by approximately 12% (DMinder, 2018; WHO, 2018).  Therefore, during daylight hours, it is primarily composed of UVA and IR radiation. Infrared (IR) light penetrates the skin several millimetres (IRA,IRB), and this is typically the heating effect that we feel on our skin, while IRC is only superficial penetration on the outer surface of the skin (ICNIRP, 2013).
Sunlight from sunrise to sunset has a spectral and colour distribution that changes throughout the day with various intensity (as depicted below). What is worth noting is the fact that in natural sunlight, there are no peaks in particular wavelengths of light, and the spectral distribution is balanced. This was further recorded by another chronobiology researcher in 2014 (below) trying to identify tuneable LED lighting for optimum circadian rhythms (Oh, Yang and Do, 2014). 
Not all light is equal
Light comes in many forms and from multiple different sources. However, depending on the light source, the colour spectrum and intensity of light can be vastly different. Although light technology is exponentially improving in the LED category, the majority of light can be categorized by the basic sources of sunlight, LED, incandescent and CFL. Each of these sources provides different visible spectrums. Of the different light sources, incandescent and halogen light bulbs produce infrared light (ie heat). Energy efficient light sources such as CFL and LED bulbs are far more efficient because it strips the IR/red light spectrums, thereby running “cooler” and thus more energy efficient. However, LED light sources have a peak in the blue wavelengths. When light sources with extreme peaks are more abundant, they may produce some adverse health effects (which will be discussed more in the next section). It may be akin to drinking so much water that it becomes toxic to the body.
Sunlight is the only light sources that is balanced across the different wavelengths. As with any type of over exposure, there are side effects and these may also have cumulative effects from past exposure history (otherwise known as ‘exposome’) (Krutmann et al., 2017). Infrared light and visible light have far more penetrating effects than UVA or UVB, yet UVA is also able to penetrate deeper into the dermal layers than UVB. Oxidative damage, reactive oxygen species  (ROS) and photoaging are some of the impacts of light on the skin (Krutmann et al., 2017). Sunlight provides 43% of visible spectrum and IRA 42%, while UV radiation is <10% and IR-B is <5% (Wunsch, 2016). Although UVC radiation does not reach the earth’s surface, the industrial and commercial applications are for disinfection (Wunsch, 2016). UVB radiation is normally associated with Vitamin D production and UVA is used for tanning (Wunsch, 2016). Opsins (OPN) are light-sensitive cell surface receptors and have numerous cellular functions (Haltaufderhyde et al., 2015).  Melanopsin (OPN4), one of several opsins, was determined to assist with blood flow by activating blood vessel relaxation when exposed to blue light at specific wavelengths of 430-460nm (Sikka et al., 2014). This was also confirmed in another study where OPN3 and OPN4 were responsible for relaxation in pulmonary arteries of rats at wavelengths of 400-460nm (Barreto Ortiz et al., 2018). OPN5 (neuropsin) was also identified in the skin which is UV sensitive in the 380nm (UVA range), and is thought to be involved in signalling pathways (Kojima et al., 2011). OPN1, a pigment receptive to blue-violet light is found in the epidermal cells of the skin (Haltaufderhyde et al., 2015). The skin was also found to convert UV radiation into several chemical, neural or hormonal signals that exerts a change in the brain via the hypothalamus, while creating systemic effects such as immunosuppression (Slominski et al., 2018). There are many other environment queues that the skin and our eyes interprets these for healthy homeostasis and physiological functions. The opsins are thought to provide some of these responses to light.  
Blue Light
Blue light spectrum occurs from 380nm to 480nm and with an abundance of blue light sources in the form of smart phones, tablets, laptops, smart TVs, LED car headlights, home lighting and LED fridge lighting, it has become ubiquitous.  So, what are the blue light sources in a modern living environment? These are your smart phones, smart TV, tablets, computer/laptop and LED lighting in the home. It can even be found in your refrigerator or your smart watch, or the headlights in your car. Smart phones and tablets are by far the more common devices that are frequently accessed by individuals, which in a 2013 Kleiner Perkins Internet Trends report, indicated that mobile users  use their devices up to 150 times a day, and in their more recent KPCB Internet Trends 2018 report, it is likely that adults spends up to 6 hours a day on digital media at an average of 4% growth each year (Kleiner Perkins, 2013, 2018).  With 76% of households allowing their child to use an internet connected device in bed before they sleep, and a growing trend to use these devices up to 5-6 hours per day, we are chronically phototoxic with blue light irradiance (FlurryMobile, 2017; OnePoll, 2017; Kleiner Perkins, 2018).  With such exposure to artificial lights and our ~90% indoor existence, it is assumed with relative certainty that we are bathed in ‘blue light’ 90% of our time. Our main exposure being our hands, neck and face. Our eyes being the main benefactor of such blue light reception via the retinal rods and cones. This has a direct signal to our suprachiasmatic nucleus (SCN) which is the master oscillator to our circadian rhythms. 

Blue light at 470nm can cause disruption to the circadian rhythm causing delayed sleep as well as behavioural issues and high corticosterone levels (Pilorz et al., 2016). This is primarily regulated by a blue light sensitive photopigment called melanopsin, generated by photoreceptive retinal ganglion cells (ipRGCs) (Lucas et al., 2014; Pilorz et al., 2016).  It also suppresses the ‘night time hormone’ called melatonin which steadily increases after sunset. The next table (below) indicates the amount of melatonin suppression by different light sources.  LED and CFL lights suppress melatonin secretion by the pineal gland by 80% and delays the onset of sleep (SPIE, 2018). Smart devices and TVs also use LED in their screens, however with much greater intensity/brightness. 
Studies have also shown that 530nm green light can also induce sleepiness while blue light at 470nm increases alertness and delays sleep, as it triggers different neural pathways in the SCN (Pilorz et al., 2016). 

The potential hazards of blue light have been in the news and media for nearly a decade and certain health movement groups advocating the use of amber glasses or goggles to protect the eyes from excessive blue light have developed a mini-industry with some loyal followers who have taken a precautionary approach to their own health. As early as 1998, researchers have published articles where blue-light induced illumination caused the apoptosis (cell death) of the retinal pigment epithelial cells (RPE) (Rózanowska et al., 1998; Sparrow et al., 2002). A pigment, known as lipofuscin, is known to accumulate with age, and thought to increase the risk of retinal damage or contribute to age-related macular degeneration (Rózanowska et al., 1995, 1998). It is this pigment that is found to create a blue-light induced mechanism which causes RPE cell death (Sparrow et al., 2002).
As of July 2018, the University of Toledo confirmed the mechanisms relating to blue light toxicity to retinal cells. Blue light phototoxicity and oxidative damage to the PIP2 in the plasma membrane of the retinal cells affects the chromophore and photoproducts (11-CR & ATR respectively) (Ratnayake et al., 2018). Blue light basically increased the cytosolic calcium resulting in excessive cell shape change leading to the death of the retinal cells (cytotoxicity) (Ratnayake et al., 2018).  
The confirmed root cause (above) to blue light phototoxicity may be one of the causes to age-related macular degeneration (AMD), leading to central blindness. However, AMD have other major risk factors such as smoking, diet, cardiovascular disease and genetics (Lim et al., 2012).
Could there be other adverse health effects caused by blue light?  

The South China Morning Post (SCMP) Newspaper reported in 2017 a myopia (short sightedness) epidemic with 20% of the primary school students having myopia and this increases to 50% in high school students and then 90% in University students, yet in the 1960’s, 20% of the Chinese population was short-sighted (SCMP, 2017). SCMP also reports that those in the countryside in poorer situations were less affected (1 in 6) and was attributed to the fact that they spent more time outdoors than their city counterparts (SCMP, 2017). This certainly correlates well to the ‘light-dopamine’ hypothesis, in which sunlight stimulates the release of dopamine in the retina and prevents myopia (Feldkaemper and Schaeffel, 2013; Zhou et al., 2017). The country children spent more time outdoors than indoors and were also not surrounded by technology screens, and a similar research also indicated that those who spent more time outdoors were less likely to have myopia (Rose et al., 2008; Sherwin et al., 2012). believes that it’s not an illness either and what the optometrists prescribe leads to the eye elongating, so it explores the options of treating the cause, and not the symptom (EndMyopia, 2018).
Circadian Rhythms
The natural day and night cycles of a 24hr day is something that’s taken for granted by many of us. Yet, with our continuous indoor existence, our bodies have been inundated with artificial light that in some cases are brighter than a midday sun. This wreaks havoc on our circadian rhythms, which is our body’s natural rhythm that indicates to us when to be alert and when to become sleepy for rest and recovery. These natural rhythms, as many of you know are the cortisol and melatonin cycles that waxes and wanes throughout the day. Cortisol is typically known as the stress hormone that increases from the time that you wake up, and peaks at midday, then gradually declines by night time.  
Yet, it’s not enough to assume that our body will adjust to the day/night cycles and have a good circadian rhythm. Circadian photoentrainment is needed to maintain a good cycle. Circadian photoentrainment starts in the eyes as they are the primary organs with multiple light sensitive pigments and photoreceptors that affect the retinal rods and cones to set the primary circadian clock in the suprachiasmatic nucleus (SCN) in the hypothalamus (Hattar et al., 2002). Through the SCN, the circadian rhythmic release of melatonin is initiated at night through the pineal gland, which is generated a few hours before the person’s bed time and peaks at 3-4am (Khullar, 2012). Yet, melanopsin (the blue light sensitive photoreceptor pigment) has the opposite effect to melatonin, and in some studies have shown to cause acute suppression of melatonin at specific wavelengths (Roecklein et al., 2013). However, the circadian clock needs to be constantly updated by photoentrainment on a daily basis to ensure all the primary and peripheral clocks are in sync (Brown and Robinson, 2004). 
The SCN is the master oscillator for the circadian clock which sets the pace for peripheral circadian clocks which governs physiological processes such as metabolism and body temperature (Mohawk, Green and Takahashi, 2012; Richards and Gumz, 2013). This is further confirmed in a 2017 study where eating at abnormal times (ie midnight snack) can also disrupt the skin’s circadian clock by affecting the expression of a DNA repair enzyme and thereby making the skin more susceptible to UV damage (Fonken et al., 2010; Wang et al., 2017). 
Shift work is a chronic form of circadian rhythm mis-matches that results in adverse health effects that increases the risks for metabolic mismatches, obesity, heart diseases, leptin resistance and cancer (Scheer et al., 2009; Gan et al., 2014; Torquati et al., 2017; Liu et al., 2018).

In a recently published study in 2017, researchers determined that a disrupted circadian rhythm increases the risk of cone photoreceptor damage since the circadian proteins in the eyes also control the bioavailability of the thyroid hormones in the eye used for cone photoreceptor maintenance (Sawant et al., 2017).

Optimal circadian rhythms are a must as there are many downstream bodily functions that maintains optimal health. 
Vitamin D
Vitamin D was first identified in 1932 by Askew with the isolation of Vitamin D1 (an artefact of Vitamin D2), and then in 1935, 7-dehydrocholesterol, pre-cursor to Vitamin D3 was identified by Windaus and Bock, and then finally in 1937, Vitamin D3 was discovered followed by the identification of pre-vitamin D3 in the skin by Dr MF Holick in 1977  (Deluca, 2014). Yet, the importance of Vitamin D was known since 1650 due to rickets disease (Wolf, 2004).  

Vitamin D deficiency is a chronic issue for all people, as we live indoors.  Generation of Vitamin D is controlled by multiple factors such as UVB availability, skin colour, age, latitude and altitude. “Vitamin D provides an innate immune response to pathogen threat” (White, 2018). 

So, what does a Japanese look like after living naked for 29 years on a deserted island at the 24th latitude? He has a dark tan from the increased melanin production that brings him to equilibrium with the environment. For a person beyond 80 years of age, you will notice that his mental acuity, body flexibility, eye sight and his calmness is far superior than the usual city dweller of equivalent age or younger. My own grandmother of 88 years shows similarity to this, despite living a bit higher latitude than the castaway, but spends the majority of her time outdoors tending to her multiple seasonal gardens. 

Vitamin D is also known to regulate the hormone, renin, which controls blood pressure, while also controlling the vascular smooth muscle to relax in the presence of 25OHD (Persson, 2003; Mead, 2008). In a 2004 study, researchers found a correlation where hypertension (high blood pressure) was more prevalent in winter than summer (Charach, Rabinovich and Weintraub, 2004). This would correlate well with the fact that there is less opportunity for UVB radiation during winter when in the higher latitudes beyond 35 degrees. 

Vitamin D is a hormone that is well known for its use in calcium absorption and bone health, yet there are health issues that have been recorded where Vitamin D deficiency has been associated with obesity, depression, Rickets disease and Seasonally Affected Disorder (SAD). 

Vitamin D deficiencies may indicate associations to the pathogenesis of disease such as cardiovascular disease and autoimmune thyroid diseases such as Graves and Hashimoto disease (Kivity et al., 2011; White, 2018).

There are strong associations of a high incidence and mortality of breast cancer when Vitamin D is deficient (Garland et al., 2007). The Sunlight, Nutrition, and Health Research Centre has also correlated similar associations of  mortality to breast cancer, ovarian and colon cancer to higher latitude cities across the United States (Grant, 2018).
Vitamin D insufficiency is also one of three (3) environmental risk factors for multiple sclerosis (Pierrot-Deseilligny and Souberbielle, 2013).

Prevalence of disease to higher latitudes is a strong indicator to assume that the lack of UVB light to generate Vitamin D3 naturally in the skin can be a major factor influencing optimal health. Below are some of the research that seems to indicate such effects:
there were less incidences of childhood type1 diabetes when closer to the equator. (Mohr et al., 2008)
There is a strong correlation of Crohn’s disease and ulcerative colitis in higher latitudes (away from the equator) where UV availability is lower than the equator (Szilagyi et al., 2014)
Higher latitudes are associated with a higher prevalence of Kawasaki disease (Chang et al., 2018)
Higher prevalence of schizophrenia in higher latitudes and colder climates (Kinney et al., 2009).
Multiple sclerosis disease onset is highly significant at higher latitudes (Simpson et al., 2011; Tao et al., 2016). 
In locations of high UVB availability, colorectal cancer was less prevalent (Cuomo et al., 2013)
There is a 5 times higher risk of breast cancer for those with lower serum levels of Vitamin D3  (Garland et al., 2006).
Lower risk of prostate cancer for those that had a high level of sun exposure (Garland et al., 2006).
There is an increased incidence of leukemia in low UVB locations (Mohr et al., 2011).

However, with above such research, there are so many other variables such as the population study size, amount of time spent outdoors, season, clothing, time of day, skin colour, sunscreen use and serum Vitamin D levels can all contribute to the results. It is highly recommended to review the graphs from the studies by Mohr & Garland as there are very clear trends in disease prevalence based on latitude/UVB availability. The Vitamin D receptor (VDR) is the only receptor that is found in all cells except the mitochondrial membrane. The VDR is thought to play a critical regulatory function on all cellular growth in both normal and cancerous cells (Holick, 2004). Vitamin D is a very effective immune regulator and the activated T and B lymphocytes also have VDRs (Holick, 2004).

Theory: inflammatory bowel disease, such as Crohn’s disease are associated with vitamin D deficiency (Ham et al., 2014; White, 2018), and given recent publications on how seasonal variation plays a role in the gut microbiome (Schnorr et al., 2014; Smits et al., 2017), could Crohn’s disease and any other inflammatory bowel disease be a disease of light and/or diet? Current research have specific challenges in correlating “cause and effect” due to the diversity of microbial profiles, yet having a balanced diet in fruit and vegetables, with reductions in processed foods and meats may reduce or alleviate the inflammation (Lane, Zisman and Suskind, 2017; Rapozo, Bernardazzi and de Souza, 2017). As discussed in earlier sections where circadian rhythms influences and control metabolism and the lack of sun light affects Vitamin D synthesis, would a less diverse food (unprocessed) or consuming foods that are out of season lead to a less diverse gut microbiome? Should we really be eating coconut, honey and bananas in the middle of Winter in Melbourne, Australia? Are we eating in equilibrium with our environment? 

According to Jeff Leach (microbiome researcher who spent several years with the Hadza), the gut flora can be changed quickly in 24-72 hours (Rutscher, 2018). Other research also confirms this statement, where flora or fauna diets will rapidly change the microbial diversity (David et al., 2014). Jeff Leach found that seasonal diets of the Hadza influenced the microbiota and there were rare microbiome species that appeared and disappeared with different seasons, yet these rare species are non-existent in industrialized societies (Smits et al., 2017). Can our modern transportation technologies, shipping food from different states or countries be reducing our microbial diversity? The Hadza also had one of the more broadest range of gut flora than any other society (pre-industrialized and industrialized) (Smits et al., 2017). Jeff is currently part of a group of researchers doing ‘citizen science’ research collecting gut microbial samples across the world as a cohort study for the American Gut Project and brings together a collective view of microbial diversity (McDonald et al., 2018).  Would we see a similarity of microbial diversity for industrialized societies that are directly correlated to imported foods? 
Sleep is a necessary biological function that promotes rest and recovery. The lack of sleep can result in numerous adverse health effects. In a study of 3 pre-industrialized societies (Hadza, Tsimane & San), sleep occurred 2.5-4.4hrs after sunset (mean = 3.3hrs), an average sleep duration of 5.7 – 7.1hrs and would sleep when ambient temperature dropped and awaken before sunrise (Yetish et al., 2015).  The same study also suggested that morning light exposure rather than midday light exposure was more frequent for behavioural thermoregulation (Yetish et al., 2015). What is more consistent with this analysis is that all three locations where these societies live, the sunlight is constant and does not vary with the seasons. All three countries (Hadza in Tanzania, Tsimane in Bolivia and San in Botswana) are all near the equator but above the Tropic of Capricorn.
Yet, in a modern society, our sleep varies and with smartphones, smart TVs and Netflix, we self-sacrifice our sleep for the purposes of entertainment and “relaxation”.  However, many of us may not be getting the best sleep we can. Without focusing on mattresses, pillows and all the other accessories, are we really getting the best sleep we can? According to Harvard Health (below) a normal sleep cycle for a healthy individual would cycle between REM and non-REM sleep during a 7-hour period with 4 REM periods. 
Yet, in an industrialized society, our ability to get proper sleep is diminished by technology. In a separate telephone study of approximately 19,000 individuals, researchers found that there was impaired sleep cycles due to artificial outdoor night time lights (such as city street lights) and also contributed to dissatisfied sleep quality and daytime sleepiness (Ohayon and Milesi, 2016). 

Lack of sleep has an adverse impact to health in a number of ways: 
-amyloid accumulation in the brain after one night of sleep deprivation (Shokri-Kojori et al., 2018)
Increases irritability and reduces goal-enhancing events (Zohar et al., 2005)
Associated with headaches (Paiva et al., 1995; Kelman and Rains, 2005; Rains and Poceta, 2005, 2006; Hutter et al., 2006)
Increased risk of dying sooner (Grandner et al., 2010; Vgontzas et al., 2010)
Long term memory is affected (Havekes, Vecsey and Abel, 2012; Mander et al., 2013; Spira et al., 2013)
Associated with depression (Baglioni et al., 2011)
Reduces immunity (Irwin et al., 1996)
Reduced testosterone (ie less sex drive) (Budweiser et al., 2009; Andersen et al., 2010, 2011)
Obesity / Weigh Gain (Benedict et al., 2012; Greer, Goldstein and Walker, 2013; Markwald et al., 2013)
Reduced learning ability (Drummond et al., 2000; Stickgold, James and Hobson, 2000)

When red light was irradiated onto the whole body at night for 30mins, sleep quality can be improved (Zhao et al., 2012). Red light therapy (low level light therapy / photobiomodulation) have been used for multiple benefits such as wound healing, circadian rhythm reset, reducing inflammation and pain (Avci et al., 2013). Red light therapy is widely known in the equestrian industry to ensure the horses are well-rested at night and to ensure proper circadian photoentrainment. The stables would be irradiated in red light of specific wavelengths (after sunset). 
Practical Approach To Controlling Your Light Exposure
Protecting Your Eyes & Your Skin

In recent years, the Paleo scene has been a major supporter of “blue-light blocking” glasses. The original ones touted by the Paleo gurus were the UVEX amber safety glasses. Studies have also shown that similarly tinted glasses were successful at reducing the blue light emissions  as well as app-aware solutions that customized the colour palette (Gringras et al., 2015).

Blue Light Blocking Glasses

There were numerous other glasses that can be sourced from China, but they were of lower quality and not as effective. They also do not have any lab tested results of their blue blocking capabilities. 

There were numerous other glasses that can be sourced from China, but they were of lower quality and not as effective. They also do not have any lab tested results of their blue blocking capabilities. 

Other blue-light blocking glasses that were not tested but known are: 

Gunner Optics:  (popular in the gaming world)


ClearBlue Pavoscreen: 

SomniLight Glasses:







Sleep should typically occur a few hours after sunset (which would depend on the season, but in Winter, would be around 9:30pm) and your body should naturally wake up just before sunrise (without an alarm clock). The use of TrueDark glasses (yellow & red tint) will assist with shifting your circadian rhythms. As your skin is the largest organ, it will recognize the different environmental queues during your sleep, such as the drop in temperature early morning, as well as the incoming sunlight through your windows in your bedroom. 

Sleep may average about 6-8 hrs and a good sign of sleep would be the abundance of dreams that may be recollected upon awakening. . 

Circadian Photoentrainment

Circadian photoentrainment is the process of allowing the body to be naturally entrained to the light cycles of each day for the season. Maximal skin exposure should be targeted each morning to capture the visible, UVA and IR light produced from the morning sunrise.  This is the beginning of the morning circadian photoentrainment. 

Throughout the day

Once the sun reaches 35 degrees past the horizon, UVB becomes available for Vitamin D production. DMinder app ( should be used to get notified of UVB availability depending on my location (ie latitude) and to avoid sun burn.  Frequent outdoor skin exposure should be maximized during UVB availability, while indoors under artificial light or in front of an internet connected device (ie smartphone or laptop), the blue-blocking glasses are worn and maximal skin coverage should occur to reduce blue light exposure. 

Afternoon/Evening Routine

Enjoying the sunset is a beautiful way to finish the day, with dinner eaten within 1hr of sunset, evening activities should be illuminated by halogen or incandescent lamps, but in ideal situations, internal lighting with red incandescent light bulbs is ideal, which maximizes melatonin release and maintains night vision. Several studies have advocated the use of OLED candle lights for use at night to reduce the effects of blue light on the circadian rhythms (Jou et al., 2015). Yet, a far simpler approach would be to avoid blue light completely and use red incandescent party lights at night.

Computer & TV use at night is avoided, and if it is absolutely required, then a number of tools should be used to mitigate the effects of blue light:

Install IRIS ( or f.lux ( onto your computer. This will adjust the blue light on the screen. The personal preference is IRIS as it is far more superior in its configuration. • Change the colour of your iphone to a ‘red’ colour palette – this strips away all colour except red ( 

Cover up your skin as your skin cells have blue light receptors  (ie melanopsin) and will delay the release of melatonin. 

Cover your eyes with blue light blocking glasses, however the TrueDark Twilight or Twilight Elite glasses (red tint) are used to completely block out all colours except red. This has the effect of instantly making you sleepy. So it would be worn up to an hour before bedtime, yet wearing these spectacles can induce sleep within 15 minutes.   

Far more extreme methods of controlling your light environment would be to invest in advanced red-LED and UV lighting to optimize your circadian rhythm and supplement the lack of ability to go outdoors to for sunlight exposure. Yet, this article does not cover the specific wavelengths that should be used based on research. Researchers have also suggested the use of ‘red, amber, green & blue’ LED lighting to mimic day and night time environments while optimizing visual performance (Oh, Yang and Do, 2014).  While Dr Holick has also found that RayVio’s 293nm UVB LED lights to be far more efficient for vitamin D3 synthesis compared to natural sunlight as there are other environmental factors such as latitude, season, time of day and cloud cover that may affect optimal opportunities for the body to naturally produce Vitamin D3 (Kalajian et al., 2017). Red light therapy, such as JOOVV lighting ( can be used to improve skin health, reduce inflammation and pain and maintain thyroid health. However, what better way to get proper lighting than going outdoors in the sunshine. It’s free, it’s readily available and is far more balanced.

Equilibrium always seems to happen in nature and the body has a multitude of mechanisms to reach that equilibrium. The typical responses that we see are inflammation and/or an immune response. However, some inflammatory responses can be theorized as cancer or autoimmune diseases which may have long or short latency periods before there are any visible signs. 

Location and latitude are crucial factors to the availability of UVB radiation that facilitates the generation of Vitamin D. However, our indoor existence means that we will continue to be deficient in Vitamin D. We are meant to be outdoors with our skin exposed. We need to manage our outdoor exposure to avoid sun burn, but opportunistic in our exposure to ensure circadian photoentrainment to have a healthy circadian rhythm. A healthy circadian rhythm will ensure our circadian clocks (both primary and peripheral) are in sync.

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Senri Oiso
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