The biological effects of prolonged light exposure
Chronobiology is the science of biological cycles or rhythms - that is, periodic phenomena within organisms. Photoperiod Effects are aspects of chronobiology that arise from changes in the length of light exposure during the day – such as – but not limited to - seasonally longer or shorter days experienced at higher latitudes.
Most of what happens in our bodies, our physiology and biochemistry, is rhythmic, showing strong day-night differences. .... most of our physiology alters between day and night”
- Professor Lewis Wolpert, in the forward to "Rhythms of Life; The Biological Clocks that Control the Daily Lives of Every Living Thing", by Russell G. Foster and Leon Kreitzman, 2004, Yale University Press.
Examples of photoperiod effects in nature are seasonal changes in the hair length, or shedding of dogs and horses: changes which are modified at least in part by the length of daytime light exposure in these species; and not just the animal's environmental temperature. Seasonal changes due to, for example, changes in light intensity, temperature, rainfall, or light hue (changes in light-frequency-mixes typical of spring trigger blooming in some plants, for example) are not due to photoperiod, and therefore not photoperiod effects, per se. Some photoperiod effects are seasonal, and some are not (such as those due to unnaturally long light exposure, for example.)
For many decades the suggestion that carbon dioxide produced by mankind's industrial activities might be modifying our environment, and therefore our future health or well-being, was considered unworthy of scientific attention – largely because the effects of carbon dioxide in the atmosphere are very small compared to that of water vapor – a far more potent greenhouse gas. Similarly, the suggestion that human health might be affected by the length, timing, or even color of light that we are exposed to has only recently been given any serious scientific attention – partly due to strong correlations between breast cancer and night work - although this is only a small part of the whole story. [16084719]
Observational studies support an association between night work and cancer risk. We hypothesise that the potential primary culprit for this observed association is the lack of melatonin, a cancer-protective agent whose production is severely diminished in people exposed to light at night.
- British Journal of Cancer. 2004 March 8;90(5):941-3. [14997186]
“The risk of developing breast cancer is about five times higher in industrialized nations than it is in underdeveloped countries,” said Les Reinlib, Ph.D., a program administrator with the NIEHS’ grants division. “These results suggest that the increasing nighttime use of electric lighting, both at home and in the workplace, may be a significant factor.”
Previous research showed that artificial light suppresses the brain’s production of melatonin, a hormone that helps to regulate a person’s sleeping and waking cycles. The new study shows that melatonin also plays a key role in the development of cancerous tumors. …
The melatonin-rich blood collected from subjects while in total darkness severely slowed the growth of the tumors. “These results are due to a direct effect of the melatonin on the cancer cells,” said Blask. “The melatonin is clearly suppressing tumor development and growth.”- [ NIH news release] [ 16322268]
Sleep duration as a risk factor for the development of type 2 diabetes.
Men reporting short sleep duration (< or =5 and 6 h of sleep per night) were twice as likely to develop diabetes, and men reporting long sleep duration (>8 h of sleep per night [sleeping past dawn, into the light, one presumes - RJ]) were more than three times as likely to develop diabetes over the period of follow-up. Elevated risks remained essentially unchanged after adjustment for age, hypertension, smoking status, self-rated health status, education, and waist circumference…- Diabetes Care. 2006 Mar;29(3):657-61. [15504560]
...women sleeping 5 hours or less gained 1.14 kg... more than did those sleeping 7 hours over 16 years, and women sleeping 6 hours gained 0.71 kg... more.
Just as it was remarkably easy in the past to overlook the negative health effects of smoking, asbestos, radiation, and mercury; we have also assumed until now that any amount of exposure to light during a day is safe – almost by definition. Instead, it would be safer to conclude from the scientific evidence we now have, that for most of us, no extra exposure to light, beyond a natural period of daylight, is truly safe.
Therefore this site is dedicated to how our extended photoperiod affects human health, and in particular to the dramatically new medical and science evidence that links photoperiod to human health. Not just to breast cancer but to the broad spectrum of modern chronic illnesses that arrived with or became vastly more common after, industrialization.
Chronic illnesses such as diabetes, heart disease, depression, obesity, asthma, arthritis, eczema, Alzheimer's, Multiple Sclerosis, and so many more modern disorders are taking over our lives in the industrialized world – and these diseases are becoming still more widespread with every year, often at an acelerating rate. Now these chronic diseases, which only a generation ago were rare in the third world, are becoming shockingly frequent in newly industrializing countries too - often more frequent in the younger generation there than in Eurore or North America!
The research into the major causes of death in adults found that during the past 45 years, China has undergone a huge health transition. Infectious disease has been replaced by the same chronic killers that plague the West. ...about two-thirds of the 20,033 people who died during the research period were killed by heart disease, cancer or stroke. ...Chinese mortality rates from each of the three categories topped deaths among the same age group in the United States, according to the study.
"We are very surprised by this finding," said lead co-author Jiang He of Tulane University's Department of Epidemiology in New Orleans. "This study indicates that chronic disease is not only (the) leading cause of death in wealthy countries, but also (in) developing countries, such as China."- [China.org (AP)] [16162883] [16478900]
As astonishing as it may seem to those of us raised with ever-more artificial light from TV, video games, computers, cell phones, bedside LEDs, etc.; there is a rapidly accumulating body of evidence which suggests that extended exposure to artificial light (and therefore too little true darkness) is the largest reason why these illnesses are striking so many in industrialized and industrializing nations – this is the Photoperiod Effect.
It's not that artificial light is bad in itself, of course, but that our bodies need the true night that existed during the whole period during which we evolved. That is, we need long periods of darkness each day in order to stay truly healthy. This is because our hormone system largely controls our bodies, and night (deep darkness) controls that hormone system.
Therefore, quite new science is pointing us toward a natural path to much better health, similar to the natural food movement that brings us a bit closer to the sorts of foods our remote ancestors ate.
If you're waiting for genetic research to solve these illnesses for us and extend our lives, as so many are, you may be disappointed. Not only does our genetic heritage influence just how we respond to unnaturally long photoperiods, but a recent study showed that even in identical twins, genetics had little to do with how long we live:
“How tall your parents are compared to the average height explains 80 to 90 percent of how tall you are compared to the average person,” Dr. Vaupel said. But “only 3 percent of how long you live compared to the average person can be explained by how long your parents lived.”
- NYTimes
Twin studies show that genetic differences account for about a quarter of the variance in adult human lifespan.
- [ 16708071]
In contrast, scientists are now suddenly in agreement that sleep hygiene is vital if we want to avoid chronic diseases such as hypertension, diabetes and overweight (together called "metabolic syndrome"):
New obesity research has found that too little sleep and fats from fast food can alter a person's biology, making them more susceptible to overeating and less active, said the International Association for the Study of Obesity.
- [ Reuters]
"We know this is not about gluttony -- it is the interaction of heredity and environment."
- Kate Steinbeck, co-chair of the 10th International Congress on Obesity [ Reuters]
Medical researchers also agree that obesity is a looming disaster that is now responsible for the growth in health care costs, since it is a profound risk factor for so many chronic illnesses. To quote New Scientist magazine's index for its September 9, 2006 issue (No. 2568): “Obesity could harm us more than climate change.”
"The problem of obesity is so big it was classified by WHO - World Health Organisation - as the biggest unrecognised health problem in the world.… We've got to get a grip on this and we can't still wander around saying, 'Eeh, isn't it a problem' and we must tell people to eat less and do a bit more exercise. ... I mean that has been tried for 30 years and look at the epidemic that's gone on despite using that technique. We've got to start looking at the evidence and acting on evidence and not political prejudice or convenient cop-outs."
- IOTF head Professor Philip James [ ABC News Australia]
The World Health Organization says more than 1 billion adults are overweight and 300 million of them are obese, putting them at much higher risk of diabetes, heart problems, high blood pressure, stroke and some forms of cancer. …
Thailand's Public Health Ministry, for instance, announced Sunday that nearly one in three Thais over age 35 is at risk of obesity-related diseases.
"We are not dealing with a scientific or medical problem. We're dealing with an enormous economic problem that, it is already accepted, is going to overwhelm every medical system in the world," said Dr. Philip James, the British chairman of the International Obesity Task Force. ...
The children in this generation may be the first in history to die before their parents because of health problems related to weight...- [ USA Today]
The good news is that we can reverse the modern trend toward more obesity and chronic illness - including diseases affecting those who are not obese. We can largely restore our own health and vitality by simple measures that bring more natural darkness into our lives.
We now know that a healthy, natural night is not just a matter of getting a good night's sleep (although that's important) but a full night's worth of darkness. This lets our hormone system and every cell in our bodies (particularly our metabolism and immune system) work as it was intended, rather than slowly go awry. This is the key to reversing the current tide of chronic illness. But we're actually getting less sleep and darkness, and even less sleep than we think we are!
Although participants spent an average of 7.5 hour a night in bed, they spent only 6.1 hours asleep. New study shows people sleep even less than they think
"People don't think they get enough sleep and they get less sleep than they think," said study author Diane Lauderdale, Ph.D., associate professor of health studies at the University of Chicago. "As we learn more and more about the importance of sleep for health, we find evidence that people seem to be sleeping less and less."
Studies suggest that average sleep times have declined since 1900, when people reported sleeping nine hours a night. Studies from the 1970s reported average sleep times closer to seven hours a night.- [Eurekalert.org] [ 16740591]
1) Very consistent beginning and end times ofFive Rules for healthy nights:
2) uninterrupted 3) true darkness for at least
4) nine or ten hours, while 5) never sleeping in
during morning light. (Note! Red light at night is allowed - see - Instructions)
Returning a healthy amount of darkness to our lives is a natural thing that we can all do with minimal expense or risk, along with our regular medical treatments, not instead of them.
"When you think about it," [David Blask, M.D., Ph.D., a neuroendocrinologist with the Bassett Research Institute] added, "light at night, except moonlight, is pretty inappropriate. We didn't evolve with artificial light and it's only been in the last 100 years or so that we've had this phenomenon of artificial light." Not only did people not evolve in illuminated nights, until recently they also did not spend their days bathed in the weak lighting of the typical office (about 200 times less bright than sunlight). To get in sync with nature's rhythms, Blask said, "I think that people should have as dark nights as possible, and as bright days as possible."
- [ meteorobs.org]
After a lifetime of unequestioned use of artificial light, only going to sleep when you're too tired to stay on your feet; it may seem impossible that so many terrible consequences can arrive from using artificial light as we all now do. If you can't help thinking that this explains too much with too little, or that we'd surely know by now if this were so, that chronic illnesses are normal in older populations, etc, see the "Frequently Asked Questions (and Objections)"
document.Darkness therapy, or obtaining a more natural night, can have powerful positive effects on your health. In some cases the improvement in your symptoms may be dramatic. However, since this can make other therapies unnecessary or even dangerous, please do tell your doctor that you're getting a lot more darkness. A friend of mine with hemochromatosis got a red flashlight to use at night, and stopped staying up late - following the advice here. Her iron levels became much more normal (whether coincidentally or not – this is a single case) but her doctors continued to remove iron from her bloodstream on a regular schedule, nonetheless: making her severely anemic (this is by her report.) So do monitor yourself for significant improvements, and don't forget to report any significant changes for the better to your doctor. Don't discontinue medications on your own; almost always more and better darkness can combine with your current treatments, at least until you know you are obviously better. Keep your doctor informed.
This website is a start at explaining how this unrecognized form of environmental damage could take such a terrible, and increasing toll on our bodies and health – and how to regain that health and well-being. The site was first published on August 25, 2006. It will expand with time, including more articles that address specific chronic illnesses and the research now available pointing toward extended days under too much artificial light as the primary cause of diabetes, overweight, heart disease, Alzheimer's, mental illness and so much more. There are many additional references to not just hundreds but thousands of studies which will continue to be filled in here with time, but this is a start.
Richard Stevens, an epidemiologist at the University of Connecticut, thinks that light at night disrupts our circadian hormone levels, and as a result we are becoming ill. In a study he coauthored in 2001 he wrote that there was “mounting evidence to suggest that disruption of the melatonin rhythm may lead to chronic fatigue, depression, reproductive anomalies, and perhaps even cancer.” He also found that the risk of breast cancer was raised by 60 percent for women who worked night shifts and that, conversely, the rate was 50 percent lower for women who were blind. Stevens suspects that because melatonin inhibits estrogen from accelerating the growth of breast cancer cells, its depletion causes a greater susceptibility among women who don't get enough darkness. Stevens found that even women who didn't work on night shifts, but merely slept in a moderately lit bedroom, still had higher risk levels for breast cancer.
- “Acquainted With the Night”, Christopher Dewdney, HarperPerennialCanada, 2004, p104
According to neuroendocrinologist Russel J. Reiter of the University of Texas Health Science Center at San Antonio, the emerging science indicates that, functionally, "light is a drug"--and that "by abusing it, we risk imperiling our health."
- Does light have a dark side?: nighttime illumination might elevate cancer risk Science News, Oct 17, 1998 by Janet Raloff
http://www.findarticles.com/p/articles/mi_m1200/is_n16_v154/ai_2125028
Shakespeare may have been ahead of the game. Long before electric lights or the word "depression" existed, he called sleep the "the chief nourisher of life's feast" and the "balm of hurt minds."
at photoperiodeffect.com
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