Benefits of sun exposure, by Marc Sorenson, EdD…
Interesting research regarding the critical necessity of sun exposure continues to mount.
There is no doubt that lack of sun exposure leads to disease, and a major factor in that scenario is a disrupted circadian rhythm. Researchers have stated that “Exposure to sunlight during the day, and darkness at night, optimally entrains biological rhythms to promote homeostasis and human health. Unfortunately, a major consequence of the modern lifestyle is increased exposure to sun-free environments during the day and artificial lighting at night.” Night-shift work is one of the worst contributors to the disruption of our natural biological rhythms, also known as circadian rhythms, and it certainly defines the sun-free environment discussed. There is a strong association of night-shift work to many diseases, but one of the most prevalent of these is breast cancer.
So what is natural and good for the health? Researchers have shown that a disrupted circadian rhythm can be reprogrammed, or “entrained” by exposure to a natural summer, meaning a cycle of 14 hours, 40 minutes of summer light, to 9 hours, 20 minutes of darkness. The authors state that this “light-dark cycle programs the human circadian clock to solar time, such that the internal biological night begins near sunset and ends near sunrise.”
Such a cycle would certainly seems natural for humans who were raised on ranches or farms where the day’s activities begins early in the morning sunlight and usually end near sunset. I know, because that pattern described my youth. For primitive peoples, that cycle was probably a necessity to gather the food necessary for survival. It is now ingrained in to our DNA, and disruption leads to disease.
So how are circadian rhythms reset to help our health? According to the aforementioned research (footnote 2), it can be accomplished by either a week of natural light exposure, or a weekend spent camping in nature. I am a camper, and I know that when the sun goes down, I am ready to sleep, and when the sun rises the next morning, I’m ready to start my day’s adventures.
The message here is that daytime should be spent outside in natural light. This will probably reduce the risk of many diseases, including breast cancer. It is also imperative that our skin receives its sun exposure to produce vitamin D and other healthful photoproducts. In addition being outside in the sun will increase our production of serotonin and enhance our moods.
Safely embrace the sun and save your life! Be sure not to burn.
 Ball L, Palesh, O, Kriegsfeld L. The Pathophysiologic Role of Disrupted Circadian and Neuroendocrine Rhythms in Breast Carcinogenesis. Endocr Rev. 2016 Oct;37(5):450-466.
 Stothard ER, McHill AW, Depner CM, Birks BR, Moehlman TM, Ritchie HK, Guzzetti JR, et al.
Sun and cognitive ability by Marc Sorenson, EdD, Sunlight Institute…
If you have depression, you may also have cognitive impairment, according to older research that I just became aware of. The researchers measured cognitive abilities among approximately 14,000 depressed subjects and then exposed them to either one day of sunlight or two weeks of sunlight. They then determined if cognitive disabilities were associated with the sun they obtained.
The results were impressive: Those who were sun-deprived for two weeks had 2.5 times the risk of being cognitively impaired, compared to those who had sufficient sunlight. A one-day exposure made no significant difference in cognition.
Results of other research, based on a 15-year residential history of varying degrees of sun exposure, has also shown that cognitive impairment in persons who were below the median exposure to sun, was 88% greater than those who were above the median. The researchers mentioned vitamin D as a possible mechanism by which sun positively influenced cognition, but they also remarked that regulation of the circadian rhythm by sunlight could be a factor.
Several other studies showed a close, positive association between vitamin D levels and cognition, and as we know, vitamin D levels in most cases are a surrogate measurement for sun exposure.
The message is to get plenty of sunlight to improve mental clarity. Happy thinking!
 Shia T Kent, Leslie A McClure, William L Crosson, Donna K Arnett, Virginia G Wadley and Nalini Sathiakumar. Effect of sunlight exposure on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study. Environmental Health 2009, 8:34
 Kent ST, Kabagambe EK, Wadley VG, Howard VJ, Crosson WL, Al-Hamdan MZ, Judd SE, Peace F, McClure LA. The relationship between long-term sun radiation and cognitive decline in the REGARDS cohort study. Int J Biometeorol. 2014 Apr;58(3):361-70.
By Marc Sorenson, EdD… Sun exposure benefits…
A very important paper regarding the necessity for sun exposure has recently been published by the journal Medical Hypothesis. It is entitled Regular sun exposure benefits health, and it discusses the pros and cons of sun exposure. One of the salient statements in the paper is that intermittent sun exposure may increase the risk of skin cancer, whereas regular exposure to sunlight might benefit health. For those of us who have for years studied the beneficial effects of sun exposure, the use of the word “might” is the only drawback to the statement. There is no doubt that for the majority of the population, regular sun exposure absolutely protects and enhances health.
Among the diseases mentioned as being reduced or prevented by regular sun exposure are the following:
- Cancers: Colon, breast, prostate and non-Hodgkin lymphoma
- Multiple sclerosis
As the authors mention, most of these positive effects of sun exposure were previously ascribed to Vitamin D, but they point out that immune system function is enhanced by sun exposure beyond the effects of vitamin D, and list other non-vitamin D benefits of the sun, including:
- Production of nitric oxide
- Production of melatonin
- Production of serotonin
- Regulation of the circadian clock
I have discussed most of these items on the Sunlight Institute web site, but it was good to see new research that, in particular, separated the health benefits of sun exposure from vitamin D production. The idea that has become popularized during the past decade, that all benefits of sun exposure come from increased vitamin D production, is simply not true and can lead to the supplementation of vitamin D as a “cure” for diseases that may not be influenced by that hormone.
Of course, vitamin D is an exceptionally important photoproduct, and the only natural way to attain it is by exposure to the sun or to other sources of UVB light (such as a sunlamp or a tanning bed). The beauty of using these sources, rather than a vitamin-D capsule, is that all of the benefits of nitric oxide, melatonin, serotonin and circadian entrainment are included in the package.
Safely enjoy the sun, and you then will also safely enjoy better health. Remember not to burn, and to gradually develop a good tan.
 van der Rhee H, de Vries, E, Coebergh, J. Regular sun exposure benefits health. Medical Hypotheses 97 (2016) 34–37
By Marc Sorenson, EdD. Sunlight Institute… Sun exposure.
New research from China suggests that sun exposure, through vitamin D production, contributes improvements in bone health, mood and cognitive functions. It also says that sun exposure, through the regulation of melatonin also helps to properly establish circadian rhythms, improve sleep quality, and optimizes physical and social activity in the elderly. They might have also mentioned that cognitive decline is much more prevalent among nursing-home residents that do not participate in outdoor activity; those who have 20 or more outdoor activities per month have no decline whatsoever!
This is especially important for institutionalized elderly people who tend to spend time in their rooms and asleep in front of the TV. The researchers suggest that the elderly should perform outdoor activities for 20-30 minutes per day, five days per week. They also suggest that the outdoor environment be more accessible to the residents and that some of their programmed activities should be held outdoors.
This is excellent advice and really hits home with me, since my wife and I have a church calling in which we conduct meetings and otherwise take care of the spiritual needs of the residents at an assisted-care facility. We see the physical and mental deterioration that takes place among the people who seldom get outside. We are always suggesting to our charges, and to the people who run the facility, that they get regular sun exposure and eat correctly, both of which would make dramatic differences in their abilities to cope.
Did you know that the risk of being admitted to a nursing home can be predicted by vitamin D levels? In one investigation, those whose serum vitamin D levels were in the deficient category had three-and-one-half times the risk of being admitted to a nursing home as those whose levels were in the highest category. Of course, people with low vitamin D levels are suffering from sun-exposure deficiency. Let’s take care of our elderly by being sure that they enjoy plenty of safe sun exposure.
 Lin TC, Liao YC. The Impact of Sunlight Exposure on the Health of Older Adults. Hu Li Za Zhi. 2016 Aug;63(4):116-22.
 Suzuki T, Murase S. Influence of outdoor activity and indoor activity on cognition decline: use of an infrared sensor to measure activity. Telemed J E Health. 2010 Jul-Aug;16(6):686-90
 Visser, M. et al. Low serum vitamin concentrations of 25 hydroxyvitamin D in older persons and the risk of nursing home admission. Am J Clin Nutr 2006;84:616-22.
By Marc Sorenson, EdD. Sunlight Institute.
Regular sun exposure is one of the best ways to reduce the risk of many cancers. Although the relationship of sun exposure (and vitamin D) to the risk of prostate cancer is controversial, a study from Australia, published in 2011, showed that the less sun exposure, the greater the risk of the cancer. The researchers investigated the relationship between prostate cancer incidence and solar radiation in non-urban Australia and found an inverse association. There are many other studies that indicate a protective effect of sun exposure. One of the earliest was conducted by Dr. Esther John and her colleagues: they compared the lifetime sun exposure of 450 white men with advanced prostate cancer to that of 455 white men who did not have cancer. The men were divided into quintiles according to the amount of exposure they had received. Subjects in the highest fifth of sun exposure had only 51% of the risk of prostate cancer as did those in the lowest quintile.
Another study on cancer that corroborated these observations was entitled: Is prevention of cancer by sun Exposure more than just the effect of vitamin D? A systematic review of epidemiological studies. In their review, the authors noted that regular sun exposure correlated to a reduced risk of colorectal cancer, prostate cancer, breast cancer and non-Hodgkin’s lymphoma (NHL). However, vitamin D levels correlated to a reduced risk of colorectal, and to a lesser extent, breast cancer, but were not correlated to a significant risk reduction in prostate cancer and non-Hodgkin’s lymphoma. The authors concluded with this statement: “Particularly in prostate cancer and NHL, other sun-potentiated and vitamin D-independent pathways, such as modulation of the immune system and the circadian rhythm, and the degradation of folic acid, might play a role in reduced cancer risk as well.” These researchers did well to remind us, that as important as vitamin D is to the human body, other effects of sun exposure may be more important in some diseases. The authors could have also mentioned the effect of sun on vasodilation, mediated by the production of nitric oxide (produced by the skin after sun exposure). They could also have discussed the influence of sun on production of serotonin and endorphins, all of which may have contributed to their observations.
Other research used childhood sunburn as a measure of UVR exposure and determined that men who had sunburned as children had only about one-fifth the risk of contracting prostate cancer as those who had not sunburned. A note of caution! We are not recommending that anyone sunburn in order to prevent prostate or other types of cancer. Sunburn was used in this research to predict higher vitamin D levels, but it is not necessary to achieve those levels, since non-burning sun exposure achieves the same results. This research also demonstrated that men with lowest level of UVR exposure had more than triple the risk of prostate cancer and that onset of the disease was delayed more than four years in those who had the greatest exposure compared to those who had the least exposure. A follow-up to this study, reported that men in the lowest quartile of sunbathing were linked to a 5.33-fold greater risk of prostate cancer than those in the highest quartile. Still other research has indicated that “higher levels of cumulative exposure, adult sunbathing, childhood sunburn and regular holidays in hot climates were each independently and significantly associated with a reduced risk of this [prostate] cancer.
So men, protect your prostate by regular, non-burning sun exposure. Don’t let the Powers of Darkness frighten you away from the sun.
 Loke TW, Seyfi D, Khadra M. Prostate cancer incidence in Australia correlates inversely with solar radiation. BJU Int. 2012 Apr;109 Suppl 3:75.
 John EM, Schwartz GG, Koo J, Van Den Berg D, Ingles SA. Sun exposure, vitamin D receptor gene polymorphisms, and risk of advanced prostate cancer. Cancer Res 2005;65(12):5470-79.
 van der Rhee H, Coebergh JW, de Vries E. Is prevention of cancer by sun exposure more than just the effect of vitamin D? A systematic review of epidemiological studies. Eur J Cancer. 2013 Apr;49(6):1422-36.
 Moon SJ, Fryer AA, Strange RC. Ultraviolet radiation: effects on risks of prostate cancer and other internal cancers. Mutat Res 2005;571(1-2):207-19.
 Bodiwala D, Luscombe CJ, Liu S, Saxby M, French M, Jones PW, Fryer AA, Strange RC.. Prostate cancer risk and exposure to ultraviolet radiation: further support for the protective effect of sun. Cancer Lett 2003;192:145-49.
By Marc Sorenson, EdD, Sunlight Institute..
Just when one thinks that there is nothing new that sunlight can do, new research belies that idea. It has now been shown that among children who growth-hormone deficient, and are being treated for that deficiency, growth is more rapid during summer months. In a one-year study using 118 children from 14 countries as subjects, growth was measured and compared to the amount of sunlight received by the children. Those who were exposed to more sunlight had faster growth. The investigators also implicated a role for circadian-clock pathways in influencing growth (see my previous blogs on the importance of sunlight in correctly setting the circadian clock).
Although this research was claimed to be the first to demonstrate an influence of sunlight on accelerated growth among children being treated with growth hormone, another investigation from 2013 came to the same conclusion.  Others have also observed that children seem to grow more rapidly in summer.   
We want our children to have reasonable rates of growth, and the vitamin D produced by sunlight may produce larger and stronger bones. Or, it may be another factor such as nitric oxide, serotonin, endorphins or other less studied photoproducts. Whatever the mechanism, we now know that sunlight has one more critically important effect on human health, this time for our children.
 De Leonibus C, Chatelain P, Knight C, Clayton P, Stevens A. Effect of summer daylight exposure and genetic background on growth in growth hormone-deficient children. Pharmacogenomics J. 2015 Oct 27. [Epub ahead of print].
 Dorothy I Shulman, James Frane, and Barbara Lippe. Is there “seasonal” variation in height velocity in children treated with growth hormone? Data from the National Cooperative Growth Study. Int J Pediatr Endocrinol. 2013; 2013(1): 2.
 Marshall WA. Evaluation of growth rate in height over periods of less than one year. Arch Dis Child. 1971;46:414–420.
 Lee PA. Independence of seasonal variation of growth from temperature change. Growth. 1980;44:54–57.
By Marc Sorenson, EdD, Sunlight Institute
Are you suffering from anxiety disorder, but fear taking drugs? Your fear is well-founded. It has been shown that a class of drugs called anti-anxiety drugs, i.e. valium and Xanax, and sleep aids like Ambien, Sonata and Lunesta lead to increased risk of death.[i] During 7.6 years, and after controlling for other factors such as sleep disorders, anxiety disorders and other psychiatric illnesses, it was found that the risk of dying was 3.46 times higher in those who took the drugs compared to those who did not. Considering the material we have posted on this site regarding brain disorders, insomnia, and sunlight, it seems reasonable to believe that a better and less dangerous anxiety-treatment option would be regular sunlight exposure.
Research from Denmark has shown that morning light, made to mimic daylight, relieves anxiety by reducing the activity of the brain’s fear center.[ii] The efficacy of the light treatment was based on the intensity of the light: the greater intensity, the greater the effect.
Another scientist, Dr Klaus Martiny, commented on the above study and noted that morning light improves sleep. “A lack of daylight disrupts some hormonal processes in our body that regulate our circadian rhythm. This can result in a shift in circadian rhythm, so that people go to sleep later and later in the evenings, and this shift is associated with an increased risk of depression.”[iii]
Martiny suggested that a good rule of thumb is to go to sleep before midnight and awaken before 8:00 AM. However, we discussed in the post on obesity that the earliest morning sunlight was associated with a remarkably lessened risk of obesity, which was also attributed to resetting the circadian rhythm. We therefore suggest that a better rule of thumb is to be outside for a half-hour when the sun rises each morning.
Get your morning sunlight, your midday sunlight and your afternoon sunlight. Sunlight is the great healer.
[i] Weich S, Pearce H, Croft P, Singh S, Crome L. et al. Effect of anxiolytic and hypnotic drug prescriptions on mortality hazards: retrospective cohort study. BMJ 2014;348:g1996.
[ii] Christensen B. Morning light relieves anxiety. Science Nordic 2014. http://sciencenordic.com/morning-light-relieves-anxiety Accessed August 8, 2015.
[iii] http://sciencenordic.com/morning-light-relieves-anxiety. Accessed August 8, 2015