(Full preview of Chapter 2 from "Healthy Lighting of your Homes - Guiding principles to health efficient lighting of homes". The book is available for purchase at http://www.amazon.com/dp/B00TKSLSK4)

The Universe works with the precision of a clock. Planets revolve around the Sun at precise speeds. Satellites of planets revolve around their planets at precise speeds. The moon rotates around our planet earth at precise speeds. Many of these planets also spin around their own axis.

Fig 2.1 Atomic universe clocks

All these gravitational rotations create natural cycles which ensure balance and regulate earth and its atmosphere. These rotations are so accurate, that there is only a 2 millisecond slowing down, in 100 years. The most accurate clock in our world is not a manmade clock with springs and gears but a natural clock. The accuracy of the oscillations in a caesium atom (9,192,631,770 cycles per second) is harnessed to create atomic clocks, which is the master clock of our world. This master clock is used as a reference by other time sensitive secondary clocks as in GPS information for naval systems, Air traffic systems and other applications like internet trading and telecommunications etc.. Our flights land safely, ships reach their shores thanks to the accurate vibrations in a caesium atom. The accuracy of the master clock is vital for the safe and sound functioning of the secondary clocks. Even an error of a few milliseconds could be fatal for individuals and the economy.

Biological Clocks

Similar to the master clock in our external world, we have a master clock inside our body called the SCN (Supra Chiasmatic Nucleus). It is a small group of fifty thousand brain cells, located in the hypothalamus, each having their own frequency of oscillation and control a mind boggling array of our physiological and psychological responses. It is like having 50,000 atomic clocks working in sync with each other and regulating thousands of secondary atomic clocks in an oscillatory orchestra. There are secondary clocks in our body which reset their times in sync with the master clock to complete their functions. All these triggers and responses have their own unique natural frequencies and complex interdependencies that each complete their cycle of operations as a synchronous orchestra but with unique phase shifts. (fig 2.2). Each cell has a different time, maintaining their individual delay from each other, while being a part of a cascade of events. As we will see in the response of photo receptors, small stimuli being snow balled into a strong response, is a direct result of a hierarchy of biochemical reactions with this synchronous delay. These are so accurate and reliable that any disorder or absence of these oscillations distinguishes between life and death or illness and wellness. Cycles with periods less than 20 hours are called ultradian rhythms, while cycles with periods longer than 28 hours are called infradian cycles. These two are commonly associated with cycles less than 24 hours and longer than 24 hours. Circadian rhythms are cycles with a period close to 24 hours. It means about a day. (circa – about, dies – a day). Heart rate is one such ultradian oscillation we can easily relate to. But the level of sodium ions in a cell, hormone secretions or stages of sleep also have their own frequencies of oscillation. Chronic deviations from these natural frequencies of operation result in health complications.

Biological Clocks

Fig 2.2 Biological Rhythms

Even the triggers or stimuli have to be present or absent at specific frequencies for effective responses. Light is one such primary stimuli to the master clock (SCN) that it triggers off a cascade of electrochemical signals throughout our entire body, with the help of our secondary clocks (fig 2.3). The optic nerve from the eyes, carries nerve signals from the light sensitive ganglion cells to the SCN, hypothalamus and the pineal gland ( non-visual circuitry). SCN is called the ‘third eye’, Hypothalamus is referred as the ‘brain’s brain’ and the pineal gland is called the ‘regulator of regulators’. Detection of light triggers the master controllers of the brain, eventually regulating most of our body functions and emotions of the daytime circuitry. Absence of light triggers a different set of responses which activates the night time circuitry in the brain. While the light and dark stimulus were in circannual balance for millions of years, duration of light stimulus has increased thereby reducing the dark stimulus, throughout the year. This asymmetric exposure to light and dark stimulus seems to have started to create complications at multiple levels. We have lost both the intensity variations in a day and the photoperiod variations in a year.

Fig 2.3 – Supra Chiasmatic Nucleus (SCN) – The Master Clock

Much like the caesium atomic clock measuring time, based on oscillating frequency between different energy states, SCN, measures time based on the duration of light and dark stimulus between the days. Though it can work independently without any external cues, its natural duration is around 24.2 to 25.5 hours. Even if it continued for a 3 week duration, without light as a cue, on a free run, whatever we are doing in the daytime, we would be doing it in the night time Hence, SCN, the master clock in our body, needs the light stimulus every day, to reset itself every 24 hours, if we are to have a healthy life style. Organisms have recorded anticipatory responses and also recorded cycles of time that has passed. Orientation of sunflower to the east and cortisol release in humans well ahead of sunrise, are clear examples of anticipated response of organisms. Bands found in corals, growth rings in tree trunks and sedimentary rocks are good records of the time past. These natural clocks suggest that the earth was spinning faster in the past and that it is gradually slowing down. It is believed that the earth day was about only 6 hours long during its birth and records even 350 million years ago indicate an earth day to be around 22 hours. Could our circadian rhythms be the records for the earth’s rotation in our era? Our current biological clock duration of 24.2 to 25.5 hours have resulted in the proposition of various theories.

Our earth is slowing down by approximately 2 milliseconds for every 100 years, meaning that our earth day is getting longer by 2 milliseconds. It would take another 3 million years for our earth to be slower by a minute. It would take 180 million years for our earth to be slower by an hour to have a 25 hour day and night cycle. With our earth’s rotation still at 24 hours, is our internal system anticipating the future and responding accordingly? Too farfetched for anticipation. What would take millions of years of evolution, has our society coerced it upon itself in a few decades? Only time will tell. The most probable cause suggested by scientists is the long list of sleep problems we have due to the disruption of our circadian rhythms by artificial light sources. As we are exposed to more artificial light beyond sunset, our biological day gets extended thereby shortening our biological night proportionately.

Our internal systems are used to changes in day and night length, with near equal lengths of day and night in equinox and asymmetrical lengths of day and night in solstice. Even this is a balanced oscillation like a clock work, only that our earth clock goes on an elliptical rotation around the sun instead of a circular rotation in a clock. Our circannual systems are used to longer days and shorter nights during spring and summer and shorter days and longer nights during autumn/fall and winter with proportional activity and sleep duration as oscillations in a circannual rhythm. The artificial light stimulus in our modern society, has created an artificial sun which is stuck at the spring and summer solstice, with longer days and shorter nights, throughout the year. A sleep deficit of around 6 months from our circannual arhythms, could be impacting our health more intensely than our circadian arhythms. The whole emphasis seems to be on our circadian rhythms than our circannual rhythms of activity and rest. As with many scientific theories that sounded convincing at one stage of our evolution have been proved untrue at a later date, all these theories could either be proved right or wrong, later. While many mechanisms of circannual rhythms are yet to be understood, importance of light and dark cycle as a stimuli is well recorded. Proportion of the duration of light availability to the duration of absence of light is a key indicator of the seasons. Probably special photoreceptors like or similar to ipRGC record these varying proportions of light and dark cycles for recording circannual rhythms. With a gene ancestry of mammals going in to hibernation in winter, we seem to be having the same photoperiodicity found in many of these mammals. Typically these mammals gain in body weight during spring and summer, with lots of fat stored as reserve for the winter hibernation. With our perpetual summer from the inappropriate use of artificial light, is our body becoming obese in preparation for the never coming winter?

In the natural setting, the length of day would have been equal to the length of night, at the equator, at every stage of the earth’s slowdown. During a 12 hour day, ‘WE’ would have had 6 hours a day and 6 hours at night. During the 20 hour day, ‘WE’ would have had 10 hour day and 10 hour night. But, the proportion of day and night durations become asymmetrical, as we go away from the equator towards the poles, for at least six months, because of the earth’s tilt. As special cases like the arctic where the sun never sets for 2 months and never rises for 2 months, organisms seem to be throwing away their circadian patterns at will. But for astronauts on a low earth orbit in space, who face 45 minutes of day and 45 minutes of night, as their space shuttle rotates around the earth every 90 minutes and for the people on earth, deviating from the circadian and circannual rhythms seem unhealthy. With most of our biological responses entrained to oscillate between cycles and counter cycles as dictated by the light and dark phases of our planet, this asymmetrical extension of day and shortening of night with artificial light, throughout the year, is creating a huge deficit in our sleep and hence in our health and productivity.

Clock mechanism

Depending on the time of the day you are exposed to this resetting light stimulus, you are either an early bird or a night owl, as your internal clock is reset according to the timing of this light stimulus. Light is the Zeitgeber – Time giver, to the SCN. Other external cues like exercise, food and other social factors also can influence the master clock, but light is the strongest stimulus. Variations in these external cues, on a daily basis, can upset the time accuracy of the cycle and in turn affect the input to the secondary clocks.

The secondary clocks (peripheral clocks/subordinate clocks) in the heart, kidney, adrenal cortex, liver, spleen, pancreas and white and brown adipose tissues etc., refer to this master clock, SCN to synchronize their own clocks. While it is easy for us to visualize a pulsating heart, it is difficult to appreciate the fact that every organ, cell, organelle, molecules and atoms have an inbuilt clock ticking away at their own frequencies. Major physiological functions of our body like body temperature, hormone secretion, urine production, blood circulation, metabolism, and even the growth of hair and psychological functions of our mind like happiness, alertness, mood, emotion, cognition, memory etc., oscillate with the time of the day .

Fig 2.4 – Secondary Clocks

It has been found that every organ of our body has a time band when it responds best to medication. Fig 2.4 shows the prime time for different organs in ancient healing systems., Surprisingly, many of the circadian responses we have observed with modern equipment correlate well with this ancient wisdom. It doesn’t mean that the organs do not work in other time bands, it is just that they are more efficient at these time bands. A new trend of medical treatment, Chronotherapy, has emerged where many of the organ specific treatments are provided at its efficient response time in the day. To cite some examples of natural clock work, our body temperature is at its highest in the evening, probably from our habit of capturing and storing solar energy from dawn and lowest in the early morning hours, probably by harvesting the stored energy for repair and growth of our cells, throughout the night, which could lower the body temperature by day break. Natural deaths and births are supposed to be happening more at predawn hours than any other time of the day.

While there are many neuroendocrine and neurobehavioral responses to light stimulus, we will focus mainly on the hormone secretion response. Even further, we will focus only on three important hormones, which are critical for the balancing of activity and rest, keeping in sync with the natural light and dark cycle. On detection of light by our retina and skin, Cortisol and Serotonin are released and in the absence of light, Serotonin is converted into melatonin. Cortisol is a stress hormone, which is produced from around 3 am onwards in the adrenal cortex. It stimulates metabolism again and prepares the body for the day ahead. The first light of the day stimulates the SCN circuitry, which suppresses the production of melatonin in the pineal gland. As the day progresses, cortisol levels fall gradually throughout the day. Serotonin is more of a neurotransmitter than a hormone, produced in the brain and intestines. It produces a sense of good mood and well-being. As the cortisol levels gradually fall as a counter cycle to melatonin, serotonin helps us achieve a number of performance peaks throughout the day.

Serotonin is supposed to control impulses and improve willpower. If we do not get enough day time light, especially, the shorter wavelength - blue,  the serotonin levels would be low, resulting in impulsivity, aggression, addictive behaviours, depression and problem analysis mode(procrastination). Higher serotonin levels result in calm and controlled, happier moods with lots of willpower and problem solving mode (Proactive) with high creativity. In the evening, as our eyes sense darkness for a certain duration, the available serotonin is converted to melatonin, which makes us feel tired, slows down body functions and lowers activity levels to facilitate a good night’s sleep. In the deep sleep phase the body releases growth hormones which regulates metabolism, protein production, burning of fats, growth, strengthening of bones, cell repair, etc..

Melatonin is a strong anti-oxidant, which means it slows down the ageing process and it is thought to protect us against Alzheimer’s disease, cancer, obesity, heart diseases and diabetes etc. Absence of light triggers the visual circuitry to signal the pineal gland to start conversion of serotonin to melatonin. The quantum of melatonin production will be directly proportional to the quantum of serotonin produced during the day. If our body does not get enough daytime light, it produces low serotonin levels, which consequently produces low melatonin levels in the night. Cortisol production is inversely proportional to the melatonin level. Hence, lower melatonin levels mean higher cortisol levels. The earlier we get exposure to daytime light in the morning, our nocturnal melatonin production occurs sooner. The reverse is also true.

With already a low level of serotonin available to convert to melatonin, if we are exposed to higher lighting levels in the night time from electric lights, watching TV, mobile phones, laptops etc., the conversion of serotonin to melatonin is inhibited by the pineal gland, making it difficult for us to sleep. To complicate matters further, most of these display sources are rich in blue color, which makes our system to falsely believe that it is daytime. With lower melatonin levels, we do not sleep properly and the cortisol levels go above normal. Higher cortisol levels means higher level of stress. Stress means fight or flight mode and the entire blood supply goes to the primitive part of the brain, the hippocampus, by sucking out the blood from the new portion of the brain, prefrontal cortex. Reasoning, planning and executive decisions are some of the functions of the prefrontal cortex which get affected, resulting in impaired cognitive performance (poor intelligence). The fight or flight mode also shuts down immune functions, resulting in a weak body. Higher stress sends the blood supply from the viscera to the hands and feet for fight or flight response resulting in dampened thyroid function, blood sugar imbalances, higher blood pressure and increased abdominal fat (impaired gluconeogenesis) etc.

Abnormal levels of all these hormones at abnormal hours seem to be responsible for all the life style diseases prevalent today. Non entrainment to light and dark cycle leads to sleep, endocrine and neurobehavioral impairments, Autism spectrum disorders (ASD), Attention deficit hyperactivity disorder (ADHD), obesity, diabetes, cancer, depression, stroke and many other lifestyle diseases impacting even future generations.

What we know scientifically today, seems to have been understood intuitively, by our ancestors. Benjamin franklin’s quote “Early to bed, early to rise, makes a man healthy, wealthy and wise” makes more sense, now. In ancient Indian scriptures, the importance of waking up before sunrise, the ‘Brahma Muhurtham’ is captured in the following verse “brahmi muhurtam uttishthet swastho rakshartham ayusha: tatra sarvartha shantyartham smareccha madhusudanam”. The line translates as: ‘One should wake up in the brahma muhurta for sustaining perfect health and for achieving a long life span, as desired.’ In fact, the complete 24 hours is divided in to 8 yamas of 3 hours or 16 yamardhas of 1 hour and 30 minutes each, based on the time of sunrise, for performing daily rituals to achieve health, wealth and wisdom. Many of our activities, like attention, energy levels, sleep etc. have a period of 90 minutes ultradian rhythms that many time management and productivity strategies have been proposed around this rhythm. While our current working hour durations do not have any scientific basis, hopefully, these new understandings and realizations would result in a biologically effective time management in the work place.

While light has been glorified throughout our history, darkness has been maligned, unfairly, throughout the ages. This constant fear mongering meant that mankind was always attempting to eliminate darkness from their lives. While this elimination, was working well, at a philosophical level, it has been a disaster at a physical and psychological level. With the invention of electric light and subsequent technological advancements, we had access to a reliable and cheap source of instant light. Instead of augmenting our interiors, with these lights, in the day, our society continued its attempt to eliminate darkness and used artificial light, after sunset, creating an imbalance in our steady state. For our bodies to be in steady state of health, it requires the continuous charging of our cells during optimum intensities of light and continuous discharge of our cells during optimum intensities of darkness with marked phase accuracy. Our body being an open system, dynamically interacting with the surrounding environment, is making desperate attempts to bring us back into original steady state, unsuccessfully. This failure to capture energy, metabolize the food, repair and regrow our cells is manifesting as the various lifestyle diseases.

While the myriad variations of the light and dark cycle are happening with clockwork efficiency in nature, we are either separated from these cues by our predominantly indoor working environment or by the polluted and crowded environment in the outdoor. All we need to do is to surround ourselves with the correct light and dark cycle cues and the rest will be taken care by our intrinsically efficient body. Key is to expose ourselves to daytime light which will reset our master clock, which will in turn reset the secondary clocks in our body, and actively expose ourselves to darkness in the night time, which will ensure healthy sleep, repair and maintenance of our body cells. Our exposure to darkness, nowadays, is very rare, even when we close our eyes in bed. With so much of light pollution from outside or from electronic devices inside our rooms, complete darkness is rare. It takes 30 minutes to 1 hour for the rods to adapt to darkness cue and in this time, our mind gets restless, giving us a poor quality of sleep. While most of us do sleep, only a few of us get into the deep sleep state, where the mind and body gets revived and rejuvenated by morning. It seems critical to be actively exposed to darkness or dim glow of light for an hour or two before bed time, for a high quality sleep. 

Primordial Clocks

Like the hands of a physical clock, showing us the time, our master clock needs the movement of light and darkness to sense time, at a subconscious level. Unlike the simple movement of small and large hands of a physical clock, movement of light and darkness, in our modern world, has distorted variations in intensity and color, largely influenced by densely populated buildings, weather, season and pollution.

We can revert back to our original clock with light and darkness as the hands of the clock to signal the Sunrise, Daylight, Sunset and Night. It is critical to also regulate our arousal, activity, relaxation and rest in sync with these signals.

While there is no doubt that natural daylight is the cheap and best solution for lighting up any interior, considering our lifestyle and economic compulsions, natural daylight falls short in meeting some of our present day requirements. The same properties of natural light beneficial in outdoor environments could be unfriendly in indoor environments. Natural light is unpredictable – If we were to rise with the Sun in the morning, we would be getting up at a different time every day. Cloud cover depending on the weather, pollution, smog etc., could delay the actual Sunrise. Natural light is Seasonal – Depending on the season, there could be days or weeks when the Sunlight intensities are not sufficient to signal the onset of the day. Neither can we afford to hibernate nor can we afford not to be punctual. For these reasons, we need to keep artificial lights as a backup for daytime lighting.

With the information, we have seen so far, it is imperative that we build the following layers of artificial light around us, in our homes, for the proper signalling of light and dark cycle:

Early Morning layer of light: - A high intensity rich bluish white layer of light to reset our circadian master clock.

Late Morning/Daytime layer of light – A high intensity cool bluish white layer of light to stimulate serotonin production.

Early Evening layer of light – A low intensity warm color layer of light in orange or red, for relaxation, signalling the onset of night.

Late Evening layer of light – A dim glow of warm color layer of light in orange or red, triggering the conversion of serotonin to melatonin.

Secretion of serotonin in the presence of light and conversion of the same to melatonin, in the absence of light, is not a matter of coincidence but a calculated response, evolved over millions of years. Untimely presence of light and the absence of darkness in our modern environments is having an adverse impact on our health, albeit at an imperceptible pace and intensity. In a study of 250 families of ASD (autism spectrum disorder) patients, unaffected parents of these patients had low levels of melatonin, suggesting a genetic link. ADHD (attention deficit hyperactivity disorder)  is associated with low levels of serotonin and a study even suggested a genetic pathway, where children with mothers having low serotonin levels, were more likely to have ADHD problem. Surrounding us with the timely cues of light and dark cycle could be the only effortless way to a healthy lifestyle, for generations.

As we spend the critical triggering points of the light and dark cycle, arousal, relaxation and rest at our homes, it is the ideal place to surround us with these cues.

What do you think? Share your comments below.

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I aim to spread awareness on the subject of Healthy Lighting designs to facilitate co-creation of healthy lighting at home, work and other social spaces. My posts can be accessed at Archinect  and Linkedin Group. I also have a self published book "Healthy Lighting of your Homes" at Amazon.