PhotoperiodEffect.com

2. If light was the problem, wouldn't we know by now? It has been fully two hundred years since the diseases of industrialization began their climb up to the present epidemic, after all.

Some economists call this sort of objection, an objection that points out “the fallacy of the $20 bill on the street”; arguing that there can be no easy solutions to economic problems since, if there were such answers in easy reach, someone would already have found them. If there were easy money on the pavement that could simply be picked up, surely somebody would have bent down and picked it up before this? This is the perhaps the most common, and also perhaps the strongest objection raised to any consideration of the Photoperiod Effect. So I hope the reader will pardon a very long reply – perhaps too long. Whenever you're satisfied, feel free to skip along (far along) to the next objection, no 3. The gist of much of my response, is that the history of science shows that many good ideas have been left on the ground in plain sight, even for centuries. The earth moved rapidly through space for a long time before Galileo discovered that it moved at all. Thinking what's previously been unthinkable is considerably harder than bending down to pick up a twenty-dollar bill. As well, the true extent of the photoperiod effect hasn't been in plain sight until just recently, as chronic illnesses such as diabetes, heart disease, hayfever, eczema, etc have doubled in prevalence and then doubled again, only recently reaching epidemic proportions that affect every family, and almost every individual. We became very used to artificial light well before the full extent of chronic illness in industrialized countries became apparent. In other words, if someone drops a twenty dollar bill on the pavement at night, it may indeed lie there for a long time as people pass by, until the gradually increasing light of morning reveals it to someone's stray glance. And remember – in medicine “bending down” means paying for at least one extremely expensive medical study (at some risk to your career if you are wrong.) It's not as easy as just “bending down.” This is one reason why only this year researchers seem to have discovered, or confirmed, that the current treatment for malaria, which restricts liquids to feverish patients, is not just wrong, but is actually causing 80% of patient deaths. [http://news.bbc.co.uk/2/hi/health/5346176.stm] The opposite strategy of hydrating patients, as is done for other fevers, results in vastly higher survival rates – but finding out such facts is costly, and in the current academic climate a negative result from such novel investigations can harm or destroy the investigators' careers, not just waste plenty of money.

On to the more detailed answer:

First, so much of what I'm relying on here is very new knowledge, some of it twenty years old, some of it two years old, and some of it as little as two months old or less at the time I'm writing this (2006). We've only very recently discovered even the most basic elements of our own internal clock system, or the fact that most of our hormonal changes are actually driven by this system. In the nineteenth century, it was assumed that human beings were like clocks, and would sleep at regular hours regardless of any external cues. The term “biological clock” was coined in 1935 by Erwin Bunning, a plant researcher. Constantin Von Economo observed that brain damage near the hypothalamus in encephalitis patients caused excess sleepiness. In 1932 this was confirmed when direct stimulation of the area of this area of the brain in front of the hypothalamus was shown to induce sleep. By 1948 a general area of the hypothalamus, in the forebrain, was known to be involved with circadian rhythms. Then Curt Richter produced disruptions in animal circadian rhythms in the 1960s by creating lesions in the hypothalamus. But all this progress amounted only to showing that one area of our brain could make us sleepy.

The bigger answers about what night and day mean to human beings, and our hormone system lie outside the hypothalamus. When I went to school, the function of the pineal gland was unknown. Melatonin, now known to be the master light hormone, which the pineal gland produces only during darkness, was discovered in 1958 but it was only suggested that it might affect sleep in 1978, and even that remained controversial until 1984. [http://www.mcmaster.ca/inabis98/brown/arendt0880/two.html] The critical fact that melatonin was an antioxidant was discovered in 1993 and it's role as the “master hormone” controlling most other hormones has been a recent surprise as well. Even as late as 1998 it was possible to write: “There is however very little evidence for an important function of melatonin in adult humans...” [ http://www.mcmaster.ca/inabis98/brown/arendt0880/two.html] We now know that this could hardly be farther from the truth. Melatonin is a master switch that affects nearly everything our bodies do.

The suprachiasmatic nucleus (SCN) “the body's master clock”, in the hypothalamus, was pinpointed only in the 1970s. But that the SCN was part of a light pathway, or how many vital functions it in turned controlled through hormones - heart rate, blood pressure, appetite, sleep, mood, menstrual cycles and energy levels for starters - wasn't known until the early 1990s. Sleep medicine itself was only recognized as a medical specialty by the American Medical Association in 1996, in recognition of our increasing knowledge.

Shockingly, there were still more fundamental discoveries to be made. Up until 2002 we knew that eyes had rods and cones, and thought that was it. Actually, we were certain that was it, few matters in science could have been considered more settled. Yet in 2002 science discovered the third kind of light-detecting cells hidden within the retina –the intrinsically photosensitive retinal ganglion cells or ipRGCs which tell our body as a whole that it's night or day and control most of our hormonal responses through a direct connection to the previously mentioned hypothalamus and its SCN.

These photoreceptor cells only respond to higher frequency green and blue light, so the very idea that white (or mixed frequency) light at night posed dangers to us that red light from the dwindling coals of a fire (or an older clock radio LED) doesn't and can't; wasn't even imaginable just a handful of years ago. (And as you can see at any stereo store, that knowledge hasn't trickled down to electronic manufacturers yet – they now love to use green and blue LEDs everywhere.) The actual light-detecting molecule within these ipRGC cells, melanopsin, is an even more recent and still somewhat controversial discovery within the last year or two. (If the extensive use of artificial light were only being proposed now, given these recent discoveries, even as an experiment, it would never be allowed.)

Even so, the above roll call of recent surprises and discoveries isn't complete. The key role of the intestine was unimagined until very recent years, or what its clock was like, or that most of our melatonin was produced there. We didn't know that there were hormones that controlled appetite - as opposed to brain processes - just a couple years ago. These hormones too are controlled by light. We are only pretty sure, even now, that every mammalian cell has a clock, but just what signal keeps these clocks in the right rhythm still isn't known as I write this sentence (2006).

As for practical applications, the mere idea that depression, or anything else, might be helped by being under bright light for part of the day was outlandish and clearly unscientific twenty years ago. Now it's a commonplace truth of medicine. That breast cancer might be caused in good part by shift work and extra light exposure seemed perfectly crazy just a few years ago, now it's certain, a well-established fact.

Even now many of the finer details of our internal clock are still quite obscure – such as just how nicotine boosts dopamine transmission, or whether, as seems to be the case, melatonin levels decrease steadily with age only for people who live under artificial lights, and not less industrialized populations. Come to think of it, these aren't such fine details. We still don't know everything we should have known before allowing the extensive use of artificial light, or even nearly. Believe it or not, we don't even know just why we, or any other animal, sleeps in the first place! (Which is not to say there aren't a lot of guesses.) Only late last year was it suggested that it might just be part of our ecological niche rather than serving a specific biological purpose, originally, by Jerome Siegel.

In other words, sheer ignorance and superstition about light and sleep, joined to an enthusiasm about a technology that seemed useful and pleasant have lasted very nearly nearly the whole two hundred years that have passed since gas light was introduced into the world in Paris and London. (And of course more related and similar ignorance may yet persist about light and darkness – we don't yet know what we don't yet know.) Perhaps that's not surprising, since sheer ignorance and superstition are always what precede discovery; and in the absence of knowledge we are no more wise that any of our ancestors ever were. But what's most important is that we now have a chance, by collecting and paying careful attention to our new knowledge, and to the very large number of clues from the study of individual chronic diseases; to straighten up, recognize the damage nearly every person in the industrialized world is doing to themselves by exposing themselves to artificial light indiscriminately. As soon as we recognize the increasingly obvious danger that the new science is demonstrating, we can become far healthier. We will then watch most of the chronic illnesses now plaguing us return back into the obscurity from which they came, only two centuries ago. Needless to say, the enormous and concomitant reduction in health care expenditures will work an economic revolution within our societies as well.

Research keeps popping up new surprises every year about these chronic illnesses; such as the fact that women who have flexible work hours are far more likely to have heart attacks [Prevention magazine, 2006] than those with set hours, and that patients with heart failure who regularly take harmless, fake (placebo) pills die at half the rate of those who take their placebo pills very regularly. One guesses that the patients who are able to take their fake pills very regularly keep, on average, much more regular hours, and are more likely to get to bed at the same time each night. In other words, taking placebos regularly may be a “marker” of less, and less erratic, exposure to artificial light. In all this very new research, too, we are frequently presented with much evidence pointing to the role of light in many modern illnesses – if we are just willing to imagine that such a thing is possible. This connection with light is becoming more and more obvious in the accumulating evidence, but so much of that evidence is so recent that it hasn't been gathered in one place; so even some of the most obvious connections just haven't been made before this was written. Increasingly, too, a mysterious comorbidity is showing up which links almost every chronic illness in one way or another to diabetes. As just one example, Alzheimer's, in the last year or two, is being called Diabetes 3 – simply a third kind of diabetes. Today's news, as I write this sentence, notes that “Psoriasis 'ups heart attack risk'” [http://news.bbc.co.uk/2/hi/health/6033673.stm], and such new discoveries of co-morbidity occur daily, increasingly suggesting that we really have one problem, at root, where chronic illnesses are concerned.

Much of this research, too, is very recent. The concept of “metabolic syndrome” - that diabetes, obesity and heart problems might be closely related or simply different manifestations of the same disease or cause - is quite new, and it was only in 2005 that the idea that Alzheimer's might be another (the third) kind of diabetes, first appeared. Now, increasingly, as mentioned in the answer to objection 1, scientists are being forced to consider the large range of modern chronic illnesses affecting the industrialized world as a single and rapidly increasing phenomenon, rather than as many quite separate and unrelated diseases. This growing realization of how closely linked all these diseases are, is also new.

I can't resist noting however that, needless to say, the association between chronic illness and extended light exposure could nonetheless have been discovered more than a hundred years ago if we'd been looking – if science had been executed with “due diligence”. It was the job of now many generations of scientists to ask such simple questions about the radical changes being introduced into the human environment; and then to back up those queries with experiments - but it was never done. Instead, scientists relied on the uniform opinion of other scientists and society in general, and never broke ranks to perform experiments that might show that long light exposures were or weren't perfectly safe over many decades. (In contrast the motto of the original 1660 Royal Society, transformed into something very different in 1830, promised that its members would rely on no-one's opinion, but only experiments.) This despite the fact that lab rats are uniformly given twelve hour nights so as not to cause erratic experimental results.

All human beings herd, especially in their thoughts (or organized cultures and societies would not be possible). We are not so fortunate as sheep, who get to think anything they like, so long as their bodies stay with the herd. Lamentably, history shows that this natural uniformity of thought is especially true of medical scientists, who all tend to explore one narrow “legitimized”, research avenue at a time, rather than spreading out – a procedure that rather contradicts the meaning of the word “Science” within the original Royal Society. Therefore, for nearly two hundred years it was considered unscientific and unforgivably superstitious even to raise hypothetical questions about artificial light and chronic illnesses, and it probably still is. We can only hope that no new technology could be introduced today with so little continuing scrutiny and so much naive acceptance. Certainly no-one proposing such a mass experiment today, radically altering the photoperiod of millions of human beings and then waiting to see if any harm resulted, would be able to obtain permission from any University ethics committee. More about this sort of herding in the section (elsewhere) on “Scientific Resistance”, and in the third part of this reply, however.

So our collective refusal to consider the effects that long hours under artificial lights might have, and our refusal to imagine that this is possible, has meant that only now that the exact mechanisms by which our bodies respond to light is becoming known in considerable detail, are we confronted with evidence that we finally can't wholly ignore. (But we still have to ask the right question in order to understand all the surprising new data in front of us.) In other words, Science has had to wait two centuries before being willing to ask an obvious question – are we really so unlike other animals that in contrast to them, we are not harmed by chronic changes in our photoperiods? Perhaps the motley collection of fellows gathering in the Royal Society at Gresham College in the late 1600s would have asked such daring (and obvious) questions, but the vastly greater numbers of highly disciplined and rigidly trained scientists and researchers that have succeeded them did not.

Second, indeed, fully two hundred years have passed during which the incidence of these diseases, such as diabetes or multiple sclerosis, have gradually but inexorably become more and more prevalent. It's a little like the proverbial situation of the frog sitting in some water in a frying pan, who can be boiled without ever trying to jump out, if the heat is turned up very slowly. (Note that this is a problem for frogs precisely because it's a situation frogs haven't evolved to cope with.) Two hundred years ago, when doctors were very surprised at the first sudden rise in cases of diabetes, which had been a rare disease, or the first appearance of MS or hayfever; these were still curiosities and not significant medical problems for society as a whole. Now they are obviously very troubling crises, but we are no longer surprised about their very existence, and few of us now know that they arose at the same time and in the same places where artificial gas lighting first began. (There's more on the dangers that “lagtime” can pose all by itself, even without a very gradual increase in consequences, below, under “fourth”.) This rise in chronic illnesses has been so steady, that the pace of the increase seems to have escaped general notice. Most of us don't even know that eczema, asthma, diabetes, and more chronic illnesses are actually doubling in frequency every twenty years or less. No wonder the New York Times this month called diabetes “The Stealth Epidemic” when highlighting the fact that one in eight New Yorkers is now diabetic. [Diabetes and Its Awful Toll Quietly Emerge as a Crisis, by N. R. Kleinfield, published: January 9, 2006 http://nytimes.com/2006/01/09/nyregion/nyregionspecial5/09diabetes.html] However, we know that eczema won't double again in the next twenty years (at least not in North America) because mathematically, it can't. Most North Americans now have this once rare condition. Similarly, it took some time to notice that radioactivity just might be dangerous – in the meantime manufacturers put radioactive thorium into toothpaste and laxatives as a selling point. Strange as it may seem to say now, only in 1938 was radioactivity banned from consumer products. [Bill Bryson, A Short History of Nearly Everything, Anchor, 2003, p111] Any lag time between cause and effect makes discovering a correlation very difficult indeed.

Third, it would seem that in one respect, two hundred years perhaps hasn't been enough time for this culture to begin to consider that something so simple, apparently harmless, and apparently economically useful as artificial light might have profound and terrible consequences (over decades of exposure) for so many – since such a notion is still all but unspeakable, and certainly not the sort of notion that a medical “scientist” could investigate without seriously harming their career. Despite the evidence piling up, such as the certainty now that artificial light is a major cause of breast cancer; it remains somehow unscientific and anti-modern not to embrace artificial light without any reservation, or suspicion. Yet the definition of superstition is, precisely, belief without or in spite of evidence; and that evidence is now coming in, in quantity. We now know that any light except red light during the night immediately resets the critically important human clock and halts vital melatonin production in its tracks, affecting most of our other hormones in turn. This isn't disputed, and yet no doctor advises any patient to use a red light on the way to the washroom at night. None. Generations from now, this lapse will seem inexplicable; even unimaginable. A growing mountain of experimental evidence is in fact showing us that excess exposure to light can be very harmful to human beings indeed (we've known for a long time that other animals are); but still no working scientist has thought to gather that evidence in one place or confront others with it. The thought that a light switch might be dangerous to something as wonderful as a human being remains unthinkable in this society. Yet science has been little more than a series of insults to humanity's conceits – first, that its home lies at the very center of the universe and then that we are a special species far different from all the others. We are not so special that we are invulnerable.

Some ideas are unquestionable within a given culture: so much so that you can't even become conscious of the question as a question, these axioms are unspoken. All of us feel some pull not to be to different in our thinking than others. As even the iconoclastic country singer Willie Nelson says, p88, The Tao of Willie, Willie Nelson with Turk Pipkin, Gotham Books, 2006:

“There's nothing wrong with saying what you believe... unless you believe some pretty weird shit, in which case you may want to keep your trap shut.”

This wish not to be too different than our group goes beyond imitation, and is fundamental, and as profound as it is unconscious as many experiments from psychology show (such as, famously, those of Millgram.)

One might call this phenomenon cultural stickiness. Every culture has some beliefs that are unspoken because they are so thoroughly shared that talking about them isn't necessary, but which are unshakable, and within the culture, unquestionable. For us, the benign nature of artificial light is one of those beliefs that we all grow up with, even now after a great deal of scattered scientific evidence to the contrary has piled up. Artificial light being harmful is simply something inconceivable within our culture – a question we don't ask; almost can't ask. I'm no different. I considered every other possibility first, and only after a very unusual series of periods of recovery from my own illness, correlating precisely with sharply decreased light exposure, was I able even to conceive that just possibly possibly, exposure to light might be producing these periods of recovery. Even then it seemed impossible, and I dreaded trying to tell anyone else with the same disorder that they might want to try the same protocol. Yet when I hit the internet's database of medical research (largely pubmed.com) in case there might be some shred of corroboration, I was hit instead with a whole mountain of evidence, for the most part in bits and pieces, staring me in the face. I had been successfully treating myself for winter depression with a bright light for more than two decades by that time, and thought I was carefully noting any stray variables that might be affecting my health. I was willing to consider the most outlandish forms of the hygiene hypothesis, such as that a lack of intestinal worms might be the root cause of modern ills, but I was literally unable to imagine that turning a light switch on and off might be a modern miracle with a very dark side as well.

It's understandable that cultures should be fairly rigid. As small tribal societies, considerable variation would occur over generations, despite such rigid adherence to traditional views, even if only accidentally, or through misremembering, amongst small groups. Therefore, only a very strong built-in bias towards strict adherence to traditional knowledge and belief would allow cultural knowledge to survive over many generations. But we now live in very large populations within which such random, unnoticed variation is all but impossible without being corrected by someone, and our natural cultural will to consistency over time and group agreement can become extraordinarily rigid, indeed. Literacy and film now make such cultural consistency, and rigidity more possible than ever before, over longer time spans, if that's what we wish, or drift into. At the same time more people are around to create new things, and novelties emerge more often. A discovery made by one person may eventually be shared by billions. So at the same time, group think is more rigidly maintained within subgroups such as a narrow field of science, and technology forces scientific knowledge forward nonetheless.

It might be thought that in general, scientists or experts would be less prone to unthinking rigidity. But empirical studies tell a different story. In fact, designated experts have the greatest investments in current certainties. Berkeley psychologist Philip Tetlock has used laboratory and clinical studies to find out whether experts were better at thinking independently than the rest of us, or changing their minds when the facts changed:

“Tetlock also found that specialists are not significantly more reliable than non-specialists in guessing what is going to happen in the region they study. Knowing a little might make someone a more reliable forecaster, but Tetlock found that knowing a lot can actually make a person less reliable. “We reach the point of diminishing marginal predictive returns for knowledge disconcertingly quickly,” he reports. “In this age of academic hyperspecialization, there is no reason for supposing that contributors to top journals—distinguished political scientists, area study specialists, economists, and so on—are any better than journalists or attentive readers of the New York Times in ‘reading’ emerging situations.” .... Tetlock’s experts were also no different from the rest of us when it came to learning from their mistakes. Most people tend to dismiss new information that doesn’t fit with what they already believe. Tetlock found that his experts used a double standard: they were much tougher in assessing the validity of information that undercut their theory than they were in crediting information that supported it.”

- EVERYBODY’S AN EXPERT by Louis Menand, The New Yorker, Dec 5, 2005[http://www.newyorker.com/critics/books/articles/051205crbo_books1]

No doubt, medicine is ever more complex, detailed and specialized. Yet by leaving the sciences, including medical science, more and more exclusively to experts; we have also helped ensure that any overlooked facts or causes remain overlooked. As I mention later on, the Internet, happily, can now help change this, by opening up a vast mine of data to everybody.

Fourth, it's worth exploring just why, and how profoundly, any lag-time between a cause and its effect makes discovery very difficult. Human brains, and those of every other organism, are formed to respond to immediate threats rather than abstract dangers that may arrive decades or even hundreds of years in the future. This is perhaps the largest reason why humanity has been so slow to respond to the threat of future environmental disaster, and why it took far more than a hundred years after industrialization to begin to discover the threat of global warming, etc. Even now that we know there's a problem, a big problem, we can't bring ourselves to take the situation truly seriously because dramatic consequences of what we are doing now seem at least decades away. Similarly, decades of use of artificial light generally precedes such chronic illnesses diabetes or age-related macular degeneration. In order to notice cause and effect easily and obviously, some part of the population would have had to accept all modern conveniences except any use of artificial light or to have refused absolutely all new technology introduced in the last few centuries except artificial light – something that's not likely, and hasn't happened yet, but which would have made the problem obvious by contrast. Actually, one group within modern industrialized societies has adopted this strategy in part – Mormons. It's part of their revealed spiritual knowledge that light should not be used to extend daytime too far into the night. Mormon life-expectancies are at least ten years greater than the general population. A comparison with undeveloped parts of the world might have revealed much the same; detecting whether different mixes of modern inventions and conditions being introduced in slightly different orders have produced different spectrums of illness in the population, but this was never measured. Indeed, where such experiments have been inadvertently created, such as by the introduction of Corsica and Sardinia into the European Union, and the rapid upgrade of their rural and urban electrical infrastructure to European Community levels, many papers have been written about the remarkable and sudden changes in the rates of say, diabetes or multiple sclerosis, but no attempt has been made to correlate increasing amounts of light a decade, or decades, earlier with these epidemics, because the lag time obscures the correlation. Worse still, we don't have any pain sensors to complain about metabolic syndrome, hypertension, or mitochondrial dysfunction, as is discussion in section Five of this answer, below, in more detail – one more reason why associational learning hasn't help us to figure out that our use of artificial light to lengthen our photoperiod was causing, or helping to cause, chronic illnesses.

To be very specific, when the toxic factor also takes decades to do its work, then even if the consequence is as terrible as diabetes or a stroke we simply can't learn by association that we are doing ourselves harm. Such associational learning requires repeated instances (or at least just one, earlier, very striking instance). And the brain needs to associate cause and effect – something even a lag time of an hour makes quite difficult. There is one known exception to this rule: in the case of poisoning by food, evolution has had cause to outdo itself, becoming just about as sophisticated as it can be in applying associational learning even despite hours of possible lagtime. We are actually quite likely to very strongly associate, without any conscious effort or thought, episodes of poisoning/severe nausea with whatever we ate many hours before (whether the association is accurate or not). This is most likely if we ate anything then which was new or unusual for us or which had a strong taste. This is a striking exception-that-proves-the-rule (in the modern sense of that phrase) for Skinner's psychological theory of Behaviorism, and so is often cited by professors of the psychology of learning. Because our distant, even more meat-eating ancestors encountered food poisoning very frequently, nature and the law of natural selection have thoroughly prepared us for this specific danger despite lag times of many hours. However, even in this case, a lag time of more than several hours isn't, generally learned by association. Even in pre-modern times, life was too complex and teemed with too many variables to allow this kind of long-delayed learning by association to happen in any reliable fashion. To imagine that human beings would naturally learn to associate a novel cause and a novel effect that are separated by decades is to hope for much to much. This didn't happen for the Romans with regard to lead piping, and it hasn't happened for us. Too many other things happen in the meantime for our brains to be able to guess what's truly cause and effect.

Fifth, and reinforcing the second answer above: we expect things that hurt us to hurt. That's part of our very image of danger, and humans wouldn't have survived very long if it weren't so. That is, we expect that anything that damages our bodies will also cause immediate discomfort – and this is nearly always true. But when the toxic element is not one evolution has prepared us for, no such warning system will have evolved to keep us safe, and a great deal of damage can happen before we notice. By rights, our bodies ought to writhe under constant light exposure, given the harm we already know that this will eventually do to us. But our bodies don't writhe, because long days occur only very rarely in nature, say, due to lightning strikes, forest fires, volcanoes or meteorite strikes – too rarely to pose any threat to our health. Years of very long days, one after another, never occurred to our remote ancestors, so they evolved no fear of such exposure to light, and no pain response to it, despite the damage that does result. Since we evolved while exposed to quite long nights, our bodies just ignore modern extended days under artificial light despite the harm. It took the Romans much longer than two hundred years to learn from experience about a much more obvious danger where the consequences lagged the cause by a shorter time – namely the danger from lining wine vessels with lead to “sweeten” the wine, and the use of toxic lead and antimony in cosmetics. (Antimony was used as mascara and its results are very similar to arsenic poisoning.) In fact, they never did learn. The discovery that lead was poisonous had to wait until much more modern times – even though its effects had always been very toxic, over time. In this case, not only had nature not evolved a warning system to detect lead and react to it with pain or nausea, but by happenstance, the poisonous lead in combination with acidic wine (which efficiently leached the lead into the wine) actually tasted better! During almost the entire time that human beings evolved, we had never encountered either wine or concentrated amounts of lead (the latter perhaps rarely, in drinking water, but in far smaller quantities, and one can't stop drinking water). So we had evolved no bad taste or terrible gut reaction to warn us away from lead. Therefore the consequences this new metal technology, “modern” in Roman times, were deadly and protracted for centuries on end, without the cause being detected.

But there are also modern examples of harmful things not hurting that actually involves light: take the cases of blindness caused by solar eclipses during the last century (and even now.) Staring into the sun damages our eyes, but the phenomenon of a solar eclipse is so astonishing that people do stare – and too often, become blind. We aren't equipped to feel extreme pain from staring for a long time at the sun because any other time, we don't – a little discomfort suffices to keep our glances short. And eclipses, in the days before even partial eclipses could be predicted and world travel could take us to them, were very rare. Partial eclipses went largely unnoticed in the olden days since the effect was no different than a passing cloud - no staring happened. Still worse, evolution never encountered black, exposed photographic film. It too is a modern industrial invention. Such film blocks visible wavelengths of light almost completely, so our eyes feel comfortable starting at sunspots or an eclipse for prolonged periods; but the film also lets ultraviolet light pass right through and into our eyes and ultraviolet light does most of the damage. So people who used photographic film to examine the sun decades ago; before, during and after an eclipse - which was once a popular thing to do - often became blind without feeling the slightest pain. Nature, and evolution, had never prepared their bodies or brains for a situation in which only the ultraviolet light from the sun was visible, so they had no warning system in their retinas for this circumstance. The damage itself caused no pain, but it was still very real damage.

Many other similar examples from the last two hundred years could be given, but the history radiation is probably the most spectacular example. – we feel little or nothing when struck by enough radiation to do us long term harm, so that not long after X-rays were discovered, and for some decades, shoe stores were commonly equipped with a very powerful X-ray machine that aimed through your foot up at your head looking down, to show both you and the salesperson whether the shoes you'd chosen were a perfect fit. Bad idea. But one that seemed fine for a long time, because, again, in nature we hadn't encountered a whole lot of X-rays at once, except perhaps very rarely from a nearby Supernova exploding or a ginormous sunspot. Nothing felt wrong. Even when I was young, long after those X-ray machines had been removed, it was considered amusing at a Science Fair (no less) in Calgary, Alberta, Canada to allow all visitors to hold their hands over a large chunk of Uranium so that they could literally feel the radiation (newly fissioned atoms, nuclei and protons) damaging the nerves in their hands enough to cause a tingle. Also a bad idea, but still tempting, although it was now long after the lessons of atomic bombs; because nature never had a need to equip us with a sensitive radiation detector and a pain reaction to go with it. Natural, highly concentrated sources of radiation were very rare on the surface of the earth during the time our bodies and brains evolved. There was no need to evolve protective senses and pain mechanisms, then.

Much the same story can be told of asbestos, mercury (which we children were also allowed to roll balls of from bare hand to bare hand at that same Science Fair, equally remarkably to modern ears), the removal of fiber from foods, and many other industrial products introduced since coal gasification two centuries ago. Of course, if the damage is immediate – such as ashpyxiation by gas from leaking gas lighting fixtures, it can and will be recognized. Very high ceilings were quickly introduced into homes after gas lighting was, so that leaking gas, which was lighter than air, would accumulate well above human noses and lungs. Later, noxious smelling substances were also added to such gases in order to mimic, and alarm, our natural warning systems in the case of gas leaks. But in order to mimic nature in this way, in new circumstances, we must first be very conscious of a danger. Since gas can produce immediate asphyxiation, the threat was obvious very quickly after gas lighting was introduced. Unfortunately, with light, unlike the presence of gas from coal, there are no immediate dramatic consequences or illnesses (as to why this should be, see FRO objection 3.)

Analogously, for some individuals today who have “CIPA” or “chronic insensitivity to pain”, most of the harms that would cause the rest of us agony; cause no unpleasant sensation at all. One genetic source of this syndrome is a mutation affecting the nerve growth factor receptors TrkA. Such patients' lives are always in real peril, especially as children, because they easily cause themselves severe harm without realizing it; as their injuries don't hurt. Where light is concerned, we all are suffering from an exactly similar chronic insensitivity to pain – the profound (and to too many, ultimately deadly) harm that long lit-up days do, such as very real damage to the mitochondria within our cells; doesn't feel bad at all. This lack of evolutionary preparedness for the danger of extended exposure to light also explains why “sleep-deprived people often underestimate their levels of sleepiness and functional impairment.” [http://www.sleepeducation.com/Article.aspx?id=217] More light actually makes us feel better, in fact, over the short run. Nature had no reason, in the distant past, to prepare us to avoid such harm, since artificial sources of higher frequency (green, blue, or white) light were not available. Gas, and then electrical lighting were introduced so quickly that no very gradual adaptation to them through evolution was possible.

In all these cases, we are faced with a very unusual situation, in which our bodies give us no hint of the trouble to come. Such unusual situations are also easily misunderstood, of course. It is difficult enough simply to believe what we have no experience of or haven't previously imagined possible; so we often easily misunderstand, or at least partly misunderstand, what we're presented with, as well. Willie Nelson tells an elephant-in-the-garden joke in this regard. In his words:

“Did you hear the one about the country feller who'd never seen an elephant before? He'd never seen an elephant, never heard of one, never even seen a picture of one. So an elephant escapes from the circus, and this guy looks out his window, sees it in his garden, and calls the cop.
“There's a monster in my back yard!” the feller hollers over the phone.
“A monster?” says the cop. “What's he look like?”
“He's as big as a house and has a long tail that he's using to pull up my cabbages.”
“What's he doing with the cabbages?” the cop asks.
And the feller says, “You wouldn't believe it if I told you.”

p20 The Tao of Willie, Willie Nelson with Turk Pipkin, Gotham Books, 2006

Sixth, our grasp of biology and medicine more than two hundred years ago was very primitive compared to today. The changes – the sudden, startling appearance of hay fever and the transformation of diabetes from a very rare disease to a much more common one were noted with consternation by doctors at the time, but they were at a loss to know where to begin looking for an explanation – this was long before even germ theory was considered, after all. Even during this century medicine is struggling to become more scientific: there is a very contemporary movement towards “evidence based medicine” - yet it would be laughable to try to start a similar “evidence based physics”. Physics has been evidence based for hundreds of years, now. By the time biology and medicine had begun to become more sophisticated, chronic illnesses were well-established facts of life, and not viewed as new visitors

To be quite specific, the fundamental reason even now to be suspicious of artificial light is that evolution has had the chance to adapt us to live lives with only a few hours of darkness every day, year after year. But when modern industrial chronic illnesses began to appear early in the nineteenth century, the Theory of Evolution and Principle of Natural Selection had not been published, or conceived. Gas lighting (not to mention canning, etc.) were introduced starting around 1800 - 1810, and Darwin's book “The Origin of Species” was first published in 1859. Just possibly, the course of medical history might have been different if the order of discovery had been reversed, and Darwin's Theory of Evolution had been proposed and widely accepted some decades before gas or electrical light had been introduced in Paris and London.

In that case, it seems at least possible that a serious discussion might have begun as soon as gas lighting was introduced; about whether evolution had equipped us to handle such unusually long days and short nights for years at a time. I may be giving since two hundred years ago far too much credit, but perhaps someone would even have conducted experiments or surveys to see whether the sudden rise in diabetes, first appearances of hay fever, and first cases of multiple sclerosis (all of which occurred in the urban areas first served by gas lighting and struck the medical community of the day with amazement) might just be due to the evolutionarily unprecedented amount of light people were now exposing themselves to; in which case we might just have gotten the right answer only a generation or two after gas lighting and avoided countless deaths.

Needless to say we can't know, because of course, nothing like this happened. By the time Evolution was proposed, any period of questioning about the effects or suitability of gas lighting had long passed, and it was not a novelty, but a bedrock technology of Victorian society, an absolutely accepted part of modern life which actually had a large hand in shaping that society, by allowing safe travel, shopping, education and social functions long after dark. So far as I can determine, no such question about evolution and light occurred to anyone after Darwin's work was published – anymore than it would seem likely to be an obvious or serious question to you or I, whose great-grandfathers grew up under electric lights. What we can say with certainty however, is that since modern evolutionary theory had not been discovered when the now familiar explosion in chronic and atopic (autoimmune) diseases first began in Europe, the question of whether evolution had prepared us for so much light couldn't even be asked, as such. It couldn't be conceived of, as even the terms of the question lay far in the future.

It's also worth noting that the immediate dangers of gas lighting from fire and asphyxiation were so extreme that they easily overshadowed any more remote concern about chronic disease, even had that been imagined. Even in this day and age, these dangers from gas products remain very large, throughout the less industrialized world. A recent report by the Intermediate Technology Development Group estimated that indoor air pollution from such lighting results in 1.6 million deaths worldwide every year.

Seventh, lifespan doubled in the nineteenth century [Dr. Nicolas Rolland, N14A192] as a result of the control of disease, public works, and more sophisticated knowledge of hygiene, courtesy of germ theory, and more recently, antibiotics. This immense, and seemingly general medical progress effectively masked the growing problem of chronic illness. Only in the very late twentieth century did anything like alarm begin to spread within the general population or amongst medical researchers. In this case, while progress in tackling infectious disease was a wonderful gift, it also acted something like a Trojan Horse, allowing chronic illnesses to somewhat sneak up on us, without our giving them sufficient, urgent attention during the twentieth century. These diseases were not our top priority for research or public education, or considered as a single problem. The term “metabolic syndrome”, recognizing the very strong links between obesity, diabetes, hypertension and heart disease; only became common usage during the late 1970s – although these risk factors for diabetes had been observed as early as the 1920s and “Dr. Jean Vague, in 1956, made the interesting observation that upper body obesity appeared to predispose to diabetes, atherosclerosis, gout, and calculi.” [Wikipedia]

Eighth, government and even scientific slowness can also be seen in many other cases. Where cancer is concerned, asbestos and smoking were around for still longer before society was willing to consider them health problems – when I was young, cigarette companies were still advertising the health benefits of smoking. (Although some doctors had certainly questioned the healthiness of smoking much earlier.) Again, the long lag time involved in smoking related illnesses allowed such indifference, for centuries. In truth, our present situation with light poisoning is just one more episode in a long history of countless millions of deaths from the toxic effects of technological and cultural “advancements.”

Nineth, in the case of light, it's not just that “we don't feel the pain” as described above. Unusual as the following argument may seem, there is another reason why we might be reluctant to question artificial light. In the short run at least, unnaturally long light exposure isn't just neutral, it actually just feels good. Really good. Light stimulates dopamine, which is the brain transmitter cocaine mimics. Dopamine gets us going during the day and makes us happy to be at work. We like our dopamine. A lot. And light also keeps serotonin active – the brain chemical that heroin mimics.

In other words, light is highly psychoactive, literally – light is not just like a drug, instead; nearly all drugs work precisely because they mimic the effects of light on us - they activate the hormone and neurotransmitter pathways that light itself does!

Maybe it's not so surprising then that aren't very skeptical about light – anymore than people using cocaine (the dopamine mimic) are likely to sit around talking about possible heart problems (although cocaine helps cause this) or how long it takes to recover from a stroke (although cocaine use makes this far more likely as well.) It may seem remarkable, but to repeat, all hard drugs including heroin (the serotonin mimic), even hallucinogens such as mescalin, mimic light hormones/transmitters. Alcohol and tobacco's effects are more complex but include very strong light-mimicking effects. All of which is another way of saying that artificial light after nightfall is itself is a drug, and acts as such. If it were not psychoactive, hard drugs wouldn't work in the way that they do. We would not be so surprised to hear that the health of regular drug users was not uniformly good, or that they had heart problems, so why should we be so surprised that our own health is increasingly poor or that so many of us have heart problems? Nothing else should be expected.

Historically, it's been common for societies to regard as medicinal or therapeutic whatever makes us feel better this moment – this is why coffee, chocolate and cocaine were all introduced to Europe as beneficial and powerful medicines: because they produced immediate pleasant effects even in sick people. Even bleeding was popular largely (not necessarily wholly) because bleeding sent patients into a pleasant sense of shock that removing their pain, which for centuries was taken as proof enough that the practice was medicinal. Just so, it's difficult for us to regard as harmful the light, television and computer games at night that make us feel better at that moment. A fatigued or depressed person may very briefly feel better by leaving the lights on longer in the night, and they may get a little more done, that particular day. But prolonging their day isn't helping their fatigue or depression, it's causing it, and deepening. This is why bright light (that gets us to sleep sooner) and sleep therapy are now considered so important in treating depression and bipolar illness.

Strange as it may seem to say it out loud, our descendants, who will be at least a bit wiser about the use of artificial lighting, may very well consider every one of us living today in industrialized countries - including those who watched hundreds of TV channels or played video games long into the night, or even kept a light on and read - to have been addicts, many of whom died of their addiction – by diabetes, suicide, heart disease, and more. They may very well not reserve the word “addict” only for those who turned to purchasing light-mimicking hard drugs after other ways of constantly maintaining their dopamine and serotonin levels at pleasingly high levels had slowly become less effective (after decades of stimulation by extra light.) They may freely apply the word to those of us who use the real thing - artificial light - after sunset to keep the party going, and eventually suffer health effects from the habit.

Notoriously, addicts - whose habits give them immediate pleasure after all - are prone to denial. This may be true of all of us, even if in a smaller way, perhaps. Question the benefits of the prolonged use of artificial light at night, and we might have to turn the switch to the “off” position, and then sit in the dark, which might not feel as good – starting tonight. Never mind that we'll be making more serotonin in the dark and feel far better a few years later. Turning the lights off now at sunset is not a happy thought – which can't surprise anyone who knows much about dopamine, which neurotransmitter exposure to light triggers or keeps flowing (amongst other things.) Such a bias, or even denial, doesn't have to be conscious, of course. For most addicts denial isn't a conscious strategy, or isn't at first, and for a very long time.

I'll note here that seasonally longer periods of light also make us feel better, not worse – this is reasonable from an evolutionary perspective because as long as the sun is up, we were not only still able to be active and productive, but also much more vulnerable to attack by other groups of humans and so still needed to be alert. So long as such states didn't go on for longer than a few months, and we then had equally long periods to recuperate as necessary, evolution likely had reason to actually reward us for experiencing longer, active summer days. At the least, no adaptation could really protect us from them or change the variation in photoperiod in higher latitudes. Therefore, moving into northern regions of the earth didn't cause our distant ancestors to become more wary of light or longer photoperiods, even though these were new experiences to the species. The reward system that light initiates has remained intact, and who knows, maybe even strengthened. Therefore, we're used to feeling better during longer days, and associating longer days with the most pleasant and active times of the year. Still, without winter seasons of shorter days during which we can recover, we won't continue to feel better forever.

Tenth, it is pleasant to imagine, despite historical experience, that science will save us from all possible perils. But experimental science only works if you do the appropriate experiments, and the right experiment will be performed only if you are first willing to frame the right hypotheses. This may mean framing a hypothesis quite different than that of the scientist next to you, of course; and that's something that's difficult within any tribe. More's the pity, because science is by nature something of a hit and miss affair – far more trial and error than trial and success. Although scientists would uniformly acknowledge this much, there is currently no mechanism within institutionalized science which enforces a systematic exploration of all avenues and possibilities (even by, say, assigning graduate students to be advocates of untried or unpopular ideas.) Instead, even tenured scientists are to say the least, rarely encouraged to “spread out” and investigate ideas precisely because no-one else has thought it worthwhile to do so, nor are they often rewarded for “wandering off in the weeds” this way. For generations now, and quite unlike the early Royal Society which began modern science, the common pattern is: Fail in lockstep with everyone else and your career and future research funding is secure. Fail by yourself, and what you will be soon be discovering is another career. An extended discussion of the abandonment of genuine science in contemporary culture and “antiscience masquerading as the science it has betrayed” can be found in Jane Jacobs' book “Dark Age Ahead”, Vintage Canada, 2005.

It is certainly true that funding agencies pay considerable lipservice to the importance of novelty and originality - but this only applies within the strict limits set by current professional expectations as to where the answers are already believed to lie. Rarely are peer reviewers actively and consciously seeking primarily to reward proposals that they themselves would never have submitted – yet by sheer statistical probability this is probably where the most valuable avenue of research lies. The result is overwhelming redundancy – but it can also leave immense rewards ready for the few very stubborn Einsteins who are willing even to abandon their profession (or to be abandoned by it) in order to advance knowledge within it, if that is what is necessary. Those rewards of course, are large discoveries that generations of scientists may have consistently been refusing to consider possible “on the words of everyone.” (To play upon the motto of the original Royal Society.) Science can, and must be restored to a more exploratory culture.

Eleventh, for not just hundreds, but thousands of years artificial light has been relatively rare and expensive – which is to say that it is a class distinction, because only the rich could afford it. Similarly, refined flour or white bread used to be a class distinction, and the rich ate it regardless despite the consequences, such as gout. Ironically, as is reflected in the research, in the countries which have been industrialized the longest, now, this situation is reversed (with punishing consequences to the poor.) Poor people in industrialized countries are more likely to work shift work or two jobs, or to be single, working and raising a child all at the same time. As well, even the poor can afford television and light into the night even if they can afford little else. In the most mature industrialized countries, it is now the poor who now are most vulnerable to the “diseases of rich countries” such as obesity, diabetes, asthma, hypertenstion, heart disease, and more. The diseases of light.

Twelfth, not infrequently in the history of science and human knowledge it has happened that what has not been discovered for some time, then becomes very difficult to “discover” at all, since the discovery would now upset some of the prejudices of the discipline. For example, the discovery (actually rediscovery) of “ulcer bacteria” - of Helicobacter pylori bacteria within the stomach, or the Red Shift in astronomy. Australian doctors Marshall and Warren received the 2005 Nobel Prize in medicine for the discovery of Helicobacter pylori bacteria, but it was uphill all the way. To quote the New York Times:

When two Australian scientists set out in the early 1980's to prove that a bacterium, Helicobacter pylori, caused stomach inflammation and ulcers, they met opposition from a medical-industrial complex entrenched in the belief that psychological stress was the cause.

....

The opposition we got from the drug industry was basically inertia," said Dr. Barry J. Marshall of the University of Western Australia, the other Nobel winner, and "because the makers of H2 blockers funded much of the ulcer research at the time, all they had to do was ignore the Helicobacter discovery.

....

Right from the moment in 1979 when Dr. Warren, a pathologist, first saw bacteria in stomach biopsies at the Royal Perth Hospital, he said: "I met skepticism from my colleagues who mostly did not want to know, or believe, what I was describing. Anyone could see the bacteria through a microscope, but the clinicians did not want to see them."

....

Medicine's peer-review system for deciding what articles to publish and which grants taxpayers should support "discriminate against the truly inventive, exciting, far-out ideas, Dr. Hellman said.

Peer review "tends to adhere to things that are consistent with prevailing beliefs and models," he said, and "really new ideas usually just get thought of as crazy."

....

When this reporter interviewed American medical leaders about the Australian findings in 1984, some dismissed them as unimportant because a bacterial cause of ulcers had not been discussed at recent national scientific meetings.

Reflecting on his road to the Nobel Prize, Dr. Marshall said: "In the 1970's and 1980's there was a bit of a mind-set that all the important stuff in medicine had been discovered.

[http://www.nytimes.com/2005/10/11/health/11docs.html]

So often discoveries aren't made because no-one was looking. Evidence of Viking settlements in Canada wasn't sought until very recently, and so wasn't “found” - only ploughed around. Newfoundland fisherman George Decker knew that there were very large old building foundations on his land, as other generations had known; but only when Helge Ingstad, who was searching for evidence of the Viking discovery of the North America came around inquiring, was the discovery of Viking settlements in the New World made, confirmed by the excavation of artifacts. No-one else had come looking – in good part because it seemed certain that if obvious evidence existed, it would have been discovered long before.

Thirteenth, it may be worth mentioning as well, that there is a long tradition in science of amateurs with “new eyes” making substantial discoveries in science, precisely because the common biases of those who have studied formally are obscuring the problem, or misdirecting their efforts. Galileo, after all, wasn't an astronomer, but a professor of mathematics whose skill in optics had introduced him to astronomy after he made a telescope. The list of very prominent amateurs in the history of science is long and extends into our own era: Thomas Jefferson is regarded the father of modern archeology, Gregor Mendel was a monk and gardener who made vital studies of inheritance, Joseph Priestley, the discovered carbon dioxide amongst many other things, also the incomparable electrical pioneer Michael Faraday, Henrietta Leavitt who discovered variable stars, Grote Reber who built the first radio telescope, Milton Humason, who discovered the redshift of galaxies (often credited to his employer, Hubble) began as a mule driver bringing loads up to Mount Palomar observatory, and so many more names could be added. Einstein himself was in a sense an amateur. He was a patent clerk, well trained in physics, but not employed as a physicist. Einstein was the only member of his class unable to obtain a post as a physicist, due to his very bad habit of not always agreeing promptly (or ever) with his colleagues and superiors. Still other amateurs cannot be listed as such because they undertook professional degrees simply in order to gain hearings for their amateur ideas. It is generally held that scientists tend to make their greatest discoveries when young, unless, like Watson, the co-discoverer of DNA, they switch fields in mid-career. Watson had been an ornithologist, and was at best an amateur organic chemist surrounded mostly by less than admiring professionals in the field when he pieced together the correct model of DNA. His reputation in the field was nonexistent, he had nothing to lose.

Even so, it must be said that major contributions by amateurs had become rarer as science in the last century became more technical, outsiders less welcome, professionalism more renumerative, and journals more commercial and difficult (not to mention expensive) to access – but it's very likely that the Internet is going to change this, perhaps in many fields. Just as open source software contains fewer errors because there are so many more eyes examining the code and making corrections, now that it is extremely convenient and economical for anyone who wishes to do a little human powered “data mining” amongst, say, the countless numbers of abstracts of medical studies accessible through pubmed.com; we should expect to see more significant amateur contributions to medicine, etc. In particular, we may well see more discoveries that upend professionals' expectations, coming from outsiders who have no investment in current theory and don't need to fit in with professional colleagues, but who do have the time and inclination to dive into the data themselves, forming hypotheses and exploring the existing research databases to see whether their unusual hypotheses are consistent with the available evidence. So the arrival of the Internet, which has made the very new research about human biological responses to light mentioned above available to all - and not just to invested professionals whose foundational opinions are least likely to be changed by new data - is still one more reason why the chronic deleterious effects of light are being pointed out now, and not much earlier. The day of far more “Open Science” is coming, rapidly.

In summary, a final quote from Einstein:

Concepts that have proven useful in ordering things easily achieve such authority over us that we forget their earthly origins and accept them as unalterable givens. Thus they come to be stamped as "necessities of thought," "a priori givens," etc. The path of scientific progress is often made impassable for a long time by such errors. Therefore it is by no means an idle game if we become practiced in analyzing long-held commonplace concepts and showing the circumstances on which their justification and usefulness depend, and how they have grown up, individually, out of the givens of experience. - A. Einstein, Phys. Zeitschr. 17, 101 (1916). [http://www.physicstoday.org/vol-58/iss-12/p34.html]

Fourteenth, medical science may have made a most unfortunate choice of animal models for disease, in rats and mice. Both are noturnal, creating a situation in which noticing photoperiod effects is at least difficult and confusing.

As just one example: rats form bone during the day, and bone formation is suppressed by melatonin, which is present during their active time, at night. So do we make bone when we are not active, or when it's day and there's less melatonin around? How are we supposed to guess this? Does this show us that too much light causes arthritis by favoring bone resorption, or the reverse? [Endocr Regul. 2003 Sep;37(3):163-74. Influence of lighting conditions on daily rhythm of bone metabolism in rats and possible involvement of melatonin and other hormones in this process. Ostrowska Z, Kos-Kudla B, Marek B, Kajdaniuk D.] [http://www.aepress.sk/_downloads/dl.php?from=pubmed&journal=ER&file=2003_03_163.pdf] The question isn't that difficult once we are already suspicious that light may be causing or helping to cause osteoarthritis and rheumatoid arthritis, but until then it may well prevent us from seeing the connection, since it seems to point in the opposite direction.

Fifteenth, there is a special class of scientific discoveries which, notoriously, are both hard to make and very vigorously resisted: those which make us seem much less special than we supposed. The science of chronobiology that is telling us that we are just as vulnerable to photoperiod effects as other animals, is part of a very long, very slow, and heavily resisted march of science over the last several centuries, moving away from the idea that human beings are a special creation and not a part of nature along with everything else. Copernicus showed us that the earth was not the center around which everything including the Sun rotated. Newton, that even the Solar System has no special status at the center of the universe (which he held to be infinite). Darwin, that human beings came about the way other species of animals and plants did, as part of the same natural process. All these discoveries were long delayed and met very fierce resistance.

Yet the idea that humans must somehow be special remains strong, and very much molded the opinions of the academy twenty and more years ago when I went to University. At that time, to suppose that human behavior - for example, alcoholism - might in any way be explained by genetic or evolutionary factors (given that some societies have been brewing alcohol for far longer than others) was a horror in every department, and certainly to philosophers of science. Just to have suggested such a thing, as I was so impolitic as to do, was taken as proof that one was not fit to become part of the Academy in any way. This is changing, slowly. Similarly, we are just beginning to admit that just as other plants and animals are very strongly controlled by their photoperiods, so are we. No divine providence or special status or ability has made us immune to the effects of unnaturally long light exposures, instead we have evolved under very similar conditions as have other mammals (perhaps modified a bit by the invention of fire.) We too are very strongly affected by our environment – including, and especially light.

Sixteenth, “the tyranny of custom.” Suppose we had had no means of creating or providing artificial light before this year, but knew as much about medicine as we do now. What would happen if corporations proposed to introduce the extensive use of artificial lighting after sunset, including in hospitals at night? Given the scientific knowledge we now have of medicine, hormones, and chronobiology; scientists, government and the populace would all be up in arms immediately – because we know far too much about chronobiology, and how our bodies work to just suppose that somehow such a practice would turn out to be safe. No discovery would be necessary to raise alarm bells about a practice that would change . Only the force of habit opposes alarm – despite the fact that we know that some environmental factor is behind the surge of diabetes, heart disease, and more.