There are many ways in which our Paleolithic ancestors lived completely different lives than we do, in our modern, hyper-digital world.1, 2, 3, 4 Perhaps one of the most interesting factors may be the amount of light which we are exposed to, on a near endless basis.5, 6 And I don’t mean healthy, vitamin D endowing sunlight. I mean artificial, man-made, sometimes cancerous light.7 In fact, modern life typically gives us inadequate exposure to natural light during the day, and also overexposes us to artificial light at inappropriate times (after sunset).8 Study after study has shown this imbalance has possible ties to cancer, diabetes, obesity and other health problems.9, 10, 11
Then there is the troubling fact that a lack of natural light during the day, and too much artificial light at night, causes sleep loss, in addition to the aforementioned metabolic issues.12 As researchers have known since the 1970s, the suprachiasmatic nucleus of the hypothalamus is the central circadian pacemaker in mammals.13, 14, 15, 16, 17 Disruption of the functioning of this nucleus will cause a wide array of physiological and neuronal issues.18, 19, 20
With modern lighting affecting our physiology, it is important to follow steps to help avoid these problems, if one wants to be optimally healthy. Some best practices include dimmer and longer wavelengths in the evening, as well as avoiding the blue light of our computer screens, tablets and smart phones in this time frame.21, 22 Since the estimated prevalence of of sleep-wake disorders in the United States alone is about 50 to 70 million, it is absolutely vital that you prioritize changing your habits, in regards to light exposure!23
Why is the blue light from electronic devices particularly problematic? Quite simply, it suppresses your sleep-related hormone, melatonin, as well as disrupting your bodyâs natural circadian rhythm.24 Bad news. Those that are particularly susceptible to blue light issues include shift workers, soldiers, firefighters, police officers, and students. It seems like more than a bit of a cruel irony that as we have advanced in technology, we have devolved in our health. Since our circadian rhythms taken the past three billion years to evolve, and smart phones have been around for less than 20 total years, it makes perfect sense that our bodies and brains are not yet adapted to their omnipresence in our modern lives.
It is also vitally important to change the way in which you sleep, or commonly referred to as âsleep quality.â This means a completely dark bedroom, with no light whatsoever, and also a cool temperature. Cortisol dysregulation is another issue commonly seen in todayâs modern world, and there are pro-active ways to help combat this problem. Eating a Paleo diet will ensure your hormones stay in line, and will help to effectively regulate your sleep-wake cycle. Insulin highs and lows, energy surges and crashes, and lack of nutrients can all help to disrupt sleep â especially when combined together, and added to unnatural cycles of light exposure.
Combine all of these problems with the fact that sleep loss helps to make you fat, and you can begin to see just how vital proper light cycles are to an optimally healthy life.25 Remember, electric light exposure during the night, leading to altered sleep, also disrupts your circadian rhythm.26 This results in detrimental changes to your hormones, gene expression, markers of metabolism and many other physiological parameters.27, 28, 29, 30, 31 So in conclusion, go home, turn your lights out, and get a good nightâs sleep! Your future self will thank you for it!
+ REFERENCES
[1] Spreadbury I. Comparison with ancestral diets suggests dense acellular carbohydrates promote an inflammatory microbiota, and may be the primary dietary cause of leptin resistance and obesity. Diabetes Metab Syndr Obes. 2012;5:175-89.
[2] Elton S. The environmental context of human evolutionary history in Eurasia and Africa. J Anat. 2008;212(4):377-93.
[3] Chaput JP, Klingenberg L, Astrup A, Sjödin AM. Modern sedentary activities promote overconsumption of food in our current obesogenic environment. Obes Rev. 2011;12(5):e12-20.
[4] Berthoud HR. The neurobiology of food intake in an obesogenic environment. Proc Nutr Soc. 2012;71(4):478-87.
[5] Chepesiuk R. Missing the dark: health effects of light pollution. Environ Health Perspect. 2009;117(1):A20-7.
[6] Bedrosian TA, Nelson RJ. Influence of the modern light environment on mood. Mol Psychiatry. 2013;18(7):751-7.
[7] Harb F, Hidalgo MP, Martau B. Lack of exposure to natural light in the workspace is associated with physiological, sleep and depressive symptoms. Chronobiol Int. 2014;:1-8.
[8] Wright KP, Mchill AW, Birks BR, Griffin BR, Rusterholz T, Chinoy ED. Entrainment of the human circadian clock to the natural light-dark cycle. Curr Biol. 2013;23(16):1554-8.
[9] Stevens RG, Zhu Y. Electric light, particularly at night, disrupts human circadian rhythmicity: is that a problem?. Philos Trans R Soc Lond, B, Biol Sci. 2015;370(1667)
[10] Mcfadden E, Jones ME, Schoemaker MJ, Ashworth A, Swerdlow AJ. The relationship between obesity and exposure to light at night: cross-sectional analyses of over 100,000 women in the Breakthrough Generations Study. Am J Epidemiol. 2014;180(3):245-50.
[11] Sun JL, Wu SC, Chang LI, Chiou JF, Chou PL, Lin CC. The relationship between light exposure and sleep, fatigue, and depression in cancer outpatients: test of the mediating effect. Cancer Nurs. 2014;37(5):382-90.
[12] Duffy JF, Czeisler CA. Effect of Light on Human Circadian Physiology. Sleep Med Clin. 2009;4(2):165-177.
[13] Weaver DR. The suprachiasmatic nucleus: a 25-year retrospective. J Biol Rhythms. 1998;13(2):100-12.
[14] Stephan FK, Zucker I. Circadian rhythms in drinking behavior and locomotor activity of rats are eliminated by hypothalamic lesions. Proc Natl Acad Sci USA. 1972;69:1583â1586.
[15] Moore RY, Lenn NJ. A retinohypothalamic projection in the rat. J Comp Neurol. 1972;146:1â14.
[16] Klein DC, Moore RY, Reppert SM, editors. Suprachiasmatic nucleus: the mindâs clock. New York: Oxford University Press; 1991.
[17] Ralph MR, Foster RG, Davis FC, Menaker M. Transplanted suprachiasmatic nucleus determines circadian period. Science. 1990;247:975â978.
[18] Schwartz JR, Roth T. Neurophysiology of sleep and wakefulness: basic science and clinical implications. Curr Neuropharmacol. 2008;6(4):367-78.
[19] Schwartz JR, Roth T. Neurophysiology of sleep and wakefulness: basic science and clinical implications. Curr Neuropharmacol. 2008;6(4):367-78.
[20] Welsh DK, Takahashi JS, Kay SA. Suprachiasmatic nucleus: cell autonomy and network properties. Annu Rev Physiol. 2010;72:551-77.
[21] Rahman SA, Shapiro CM, Wang F, et al. Effects of filtering visual short wavelengths during nocturnal shiftwork on sleep and performance. Chronobiol Int. 2013;30(8):951-62.
[22] Burkhart K, Phelps JR. Amber lenses to block blue light and improve sleep: a randomized trial. Chronobiol Int. 2009;26(8):1602-12.
[23] National Institutes of Health. Revision of the NIH National Sleep Disorders 2003 Research Plan. Bethesda MD: National Institutes of Health. 2003.
[24] Figueiro MG, Wood B, Plitnick B, Rea MS. The impact of light from computer monitors on melatonin levels in college students. Neuro Endocrinol Lett. 2011;32(2):158-63.
[25] Available at: http://thepaleodiet.com/sleep-loss-making-fat/. Accessed March 24, 2015.
[26] Lockley SW, Brainard GC, Czeisler CA. High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light. J Clin Endocrinol Metab. 2003;88(9):4502-5.
[27] Brainard GC, Hanifin JP, Greeson JM, et al. Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor. J Neurosci. 2001;21(16):6405-12.
[28] Wirz-justice A, Kräuchi K, Cajochen C, Danilenko KV, Renz C, Weber JM. Evening melatonin and bright light administration induce additive phase shifts in dim light melatonin onset. J Pineal Res. 2004;36(3):192-4.
[29] Ackermann K, Plomp R, Lao O, et al. Effect of sleep deprivation on rhythms of clock gene expression and melatonin in humans. Chronobiol Int. 2013;30(7):901-9.
[30] Möller-levet CS, Archer SN, Bucca G, et al. Effects of insufficient sleep on circadian rhythmicity and expression amplitude of the human blood transcriptome. Proc Natl Acad Sci USA. 2013;110(12):E1132-41.
[31] Archer SN, Laing EE, Möller-levet CS, et al. Mistimed sleep disrupts circadian regulation of the human transcriptome. Proc Natl Acad Sci USA. 2014;111(6):E682-91.
This article originally appeared on The Paleo Diet.