By Marc Sorenson, EdD, Sunlight Institute
It is becoming increasingly obvious that lack of sleep is a major risk factor for human health. In a recent study reported in the journal Sleep Medicine,[i] 2579 adults without metabolic syndrome, were assessed for sleep habits for 2.6 years to determine their risk of developing metabolic syndrome, also known as Met S. Met S is a group of metabolic disorders (high blood pressure, abdominal obesity, high cholesterol, high triglyceride levels, low HDL levels and insulin resistance) that are linked to increased risk of cardiovascular disease and type 2 diabetes. The participants were aged between 40 and 70 years.
Those who slept and average of less than 6 hours daily were 41% more likely to develop Met S than those who slept 6-7.9 hours. Among the measurements that were particularly concerning, were a 30% increased risk of high blood glucose and excess belly fat (both indications of future diabetes), and a 56% higher risk of high blood pressure. The researchers concluded that “Short sleep duration is an independent risk factor for incident metabolic syndrome in a population-based longitudinal study.”
Indeed, Lack of sleep can be deadly. Forbes Magazine online ran an excellent article on sunlight and sleep,[ii] in which they stated the following statistics: “In 2012, 60 Million Americans filled prescriptions for sleeping pills, up from 46 million in 2006.” The article discusses the potential dangers of sleep medications, showing that those who take 18 pills per year have a tripling of the risk of death compared to those who take fewer than that 18. It then describes the results of research showing that people whose workplaces have windows are able to sleep about 46 minutes per night more than those who have no natural light access. Those who had more exposure to sunlight also were generally happier, had fewer ailments and experienced better vitality than their counterparts without windows.
Many individuals have difficulty sleeping long and soundly enough to feel refreshed. A study by Dr. Julie Gammack exposed test subjects to 30-60 minutes per day of direct sunlight, and according to the Saint Louis University health web site, “Nursing home patients who were exposed to natural light had improved sleep quality, less difficulty falling asleep, fewer episodes of wakefulness during the night and greater satisfaction with the amount of sleep they got.”[iii] Other research by Dr. Ayoub and colleagues in Alexandria, Egypt demonstrated that there were several factors associated with insomnia among the elderly. [iv] Having five or more diseases was associated with a 7.5 times increased risk, anxiety was associated with a 1.9 times increased risk, and depression with a 1.74 times increased risk. There was only one factor that reduced risk. Sunlight exposure was associated with 43% reduced risk. Likely, this was due to the production of serotonin and melatonin due to sunlight exposure (see the last paragraph. Other research has shown that sleep disturbances are more common in sub-arctic areas during the dark time of the year.[v] The message? If one wants to sleep well, sunlight exposure during the day is imperative.
This research on windows is particularly interesting because the effects of sunlight in that case could have had nothing to do with vitamin D, since the sunlight exposure came through windows, which block the UVB light that produces vitamin D. It is likely that the positive effects of sunlight in this case were produced by increasing serotonin levels (a natural mood enhancer) in the brain during the sunlight exposure, and then allowing melatonin (a natural relaxer) during the night.
Lack of sleep is a common, and perhaps deadly, malady. The sun is not our enemy, but a vital friend. Embrace it, but do not burn.
[i] Jang-Young Kim, Dhananjay Yadav, Song Vogue Ahn, , Sang-Baek Koh. A prospective study of total sleep duration and incident metabolic syndrome: the ARIRANG study. Sleep Medicine 2015;16:1511-1515.
[ii] http://www.forbes.com/sites/daviddisalvo/2013/06/18/to-get-more-sleep-get-more-sunlight/
[iii] Gammack, J. Quoted in Medical News Today, April 10, 2005.
[iv] Ayoub AI, Attia M, El Kady HM, Ashour A. Insomnia among community dwelling elderly in Alexandria, Egypt. J Egypt Public Health Assoc. 2014 Dec;89(3):136-42.
[v] Bratlid T, Wahlund B. Alterations in serum melatonin and sleep in individuals in a sub-arctic region from winter to spring. Int J Circumpolar Health. 2003 Sep;62(3):242-54.
Marc Sorenson, EdD, Sunlight Institute
Those of you who follow this blog remember that one of my posts regarding weight control showed that early-morning sunlight was inversely correlated to body weight and Body Mass Index (BMI).[1] The earlier in the day the sunlight exposure occurred, the slimmer was the figure or physique.[2]
Another scientific paper was recently published that “sheds more light” on the subject of obesity. This research was conducted on mice that were placed on a high-fat diet and then exposed to non-burning ultraviolet radiation (UVR) during a three-month experiment.[3] The mice, without the benefit of UVR, would have been expected to gain weight rapidly, but when they were exposed to UVR, the weight gain was impressively reduced; the UVR treatment achieved 30-40% less weight gain, compared to the expected weight gain with the high-fat diet. The amount of UVR exposure to the mice was proportionally equal to the amount of UVR that a human would be exposed to by standing for ten minutes at noon.
Other benefits included significant reductions in glucose intolerance, insulin resistance and fasting insulin levels (all markers and predictors of diabetes), nonalcoholic fatty liver disease measures and cholesterol. All of these factors, including obesity, are part of a cluster of maladies known as the metabolic syndrome, or MetS, which is indicative of deteriorating health and susceptibility to heart disease, diabetes and death.
Other interesting findings:
Supplementation with vitamin D actually reduced the aforementioned beneficial effects. Dr. Shelley Gorman, one of the authors, made two interesting observations regarding the research:
- “These findings were independent of circulating vitamin D and could not be mimicked by vitamin D supplementation.”[4]
- “It looked like the presence of vitamin D in mice on the high fat diet prevented the [beneficial] effect of UV radiation on weight gain.”
- She also mentioned that the mechanism or weight loss may be dependent on nitric oxide (NO), which originates from diet and can be mobilized by UV radiation to become bioactive.[5]
In another part of the experiment, skin induction of nitric oxide (NO)—also a product of skin exposure to sunlight—reproduced many of the positive effects of UVR, something that vitamin D could not do.
The authors concluded their research thusly: “These studies suggest that UVR (sunlight exposure) may be an effective means of suppressing the development of obesity and MetS, through mechanisms that are independent of vitamin D but dependent on other UVR-induced mediators such as NO.”
Research continues to mount about the positive effects of sunlight that are independent of vitamin D. This should in no way be construed to diminish the vital importance of vitamin D; rather, it is to make a point that sunlight works in many ways, among which are stimulating the production vitamin D, stimulating the production of NO, stimulating the production of serotonin and stimulating the production of endorphins. Why should we be satisfied with any one of these marvelous health aids when sunlight is available? With sunlight exposure, we can have them all.
[1] http://sunlightinstitute.org/675/
[2] Reid KJ, Santostasi G, Baron KG, Wilson J, Kang J, Zee PC. Timing and intensity of light correlate with body weight in adults. PLoS One. 2014 Apr 2;9(4).
[3] Geldenhuys S, Hart PH, Endersby R, Jacoby P, Feelisch M, Weller RB, Matthews V, Gorman S. Ultraviolet radiation suppresses obesity and symptoms of metabolic syndrome independently of vitamin D in mice fed a high-fat diet. Diabetes. 2014 Nov;63(11):3759-69
[4] http://www.sciencewa.net.au/topics/health-a-medicine/item/3618-sun-shines-light-on-obesity-challenge
[5] See footnote 4.