Tag Archives: circadian rhythms

You Are When You Eat | The Paleo DietRenowned evolutionary biologist Theodosius Dobzhansky said “nothing in biology makes sense except in the light of evolution.”[1] Throughout our evolution, we have lived in daily cycles of light and dark. These cycles have led to the development of natural circadian rhythms that impact many aspects of our health and vitality.

Circadian rhythms are triggered by the bright light stimulus in the morning and darkness in the evening. The hypothalamus area of the brain – specifically the suprachiasmatic nucleus (SCN) – is the master regulator, synchronising the body’s circadian clock based on information it receives from photoreceptors in the eyes in response to light [2]. The impacts of circadian rhythm are wide-reaching;

Disruption of the circadian clock can have a big impact on the body’s ability to function optimally. Jet lag – that feeling of fatigue, disorientation and mental sluggishness after travelling through multiple time zones – is a classic example [3-6]

Unfortunately, the negative effects can be more serious than just a little sluggishness. The incidence of workplace injuries and traffic accidents increases when the clocks move forward in the spring [7, 8].

Experts are just starting to uncover the many potential ripple effects of circadian dysfunction on our health: from heart disease [9, 10] and cognitive decline [11, 12], to blood sugar dysfunction and increased diabetes risk [13]; to changes in body-fat storage and breakdown [14-16], reduced liver, pancreatic, and cardiac and skeletal muscle function [17-25].

 

Late-Night Eating & Circadian Rhythm

Today, there are many ancestral circadian mismatches with modern life. Late-night eating may be one of the most glaring incongruous elements. We’re in the midst of a weight gain and obesity epidemic with 70% of adults over the age of 20 in America are overweight or obese and 50% of the population now classified as pre-diabetic or diabetic.[26-27] A body of research is appearing showing that late-night eating may be a significant contributor [27-29].

A 2014 study of overweight and obese diabetics investigated the impacts of a late-night snack on their requirement for supplemental insulin. Subjects were divided into carbohydrate, whey protein, casein, or placebo groups. All groups required significantly more insulin after all late-night snacks, though the protein snack did compare more favourably to the carbohydrate snack [30]. These results confirmed a 2003 study on late-night eating and diabetics. This earlier study showed consistently higher blood sugar levels when snacking late at night, regardless of the macronutrient composition of the meal [31].

Why is late-night eating potentially so bad for us? One possible explanation is our circadian rhythms may prevent us from effectively managing food eaten later at night. There is evidence showing the thermic effect of food is reduced in the evening, due to the circadian regulation of insulin sensitivity, meaning your blood sugar and insulin response to carbs at night is more exaggerated than during the day [32].

 

Solutions for A Modern Circadian Mismatch

Our Paleolithic ancestors would’ve rarely (if ever) eaten after dark. Yet in today’s modern world, the light emitted from iPads, laptops, TVs and mobile devices make it far easier to stay up later at night. This presents a circadian mismatch to our evolutionary biological clocks which translates into more opportunity (and likelihood) to eat. If you’re struggling with weight gain, chronically high blood sugar, pre-diabetes or diabetes then shifting your focus to “meal-timing” can be a simple and highly effective part of the solution to improving your health.

To support a healthy circadian clock, implement the following “meal-timing” strategy:

  • Avoid eating late at night – consider abstaining from all food after 6:00 or 7:00 pm or ditch your late-night snacking while on the couch and try sipping on a herbal tea instead
  • Go for an evening walk, do some light stretching, or take a relaxing bath.

 

In my experience as a clinician, I see major progress in clients who decide to abstain from food in the evening. Once they get through the first few nights, the cravings plummet and it becomes much easier to ingrain the new habit.

Supporting your circadian clock with meal-timing strategies can be an “easy win” to restoring health and vitality [33]. It’s simple and highly effective. 

References

1. Gerhart-Hines, Z. and M.A. Lazar, Circadian metabolism in the light of evolution. Endocr Rev, 2015. 36(3): p. 289-304.
2. Guler, A.D., et al., Melanopsin cells are the principal conduits for rod-cone input to non-image-forming vision. Nature, 2008. 453(7191): p. 102-5.
3. Tapp, W.N. and B.H. Natelson, Circadian rhythms and patterns of performance before and after simulated jet lag. Am J Physiol, 1989. 257(4 Pt 2): p. R796-803.
4. Leloup, J.C. and A. Goldbeter, Critical phase shifts slow down circadian clock recovery: implications for jet lag. J Theor Biol, 2013. 333: p. 47-57.
5. Comperatore, C.A. and G.P. Krueger, Circadian rhythm desynchronosis, jet lag, shift lag, and coping strategies. Occup Med, 1990. 5(2): p. 323-41.
6. Vosko, A.M., C.S. Colwell, and A.Y. Avidan, Jet lag syndrome: circadian organization, pathophysiology, and management strategies. Nat Sci Sleep, 2010. 2: p. 187-98.
7. Coren, S., Daylight savings time and traffic accidents. N Engl J Med, 1996. 334(14): p. 924.
8. Varughese, J. and R.P. Allen, Fatal accidents following changes in daylight savings time: the American experience. Sleep Medicine, 2001. 2(1): p. 31-36.
9. Maemura, K., [Circadian rhythm and ischemic heart disease]. Nihon Rinsho, 2013. 71(12): p. 2124-9.
10. Marchant, B., Circadian rhythms and ischaemic heart disease. Br J Hosp Med, 1996. 55(3): p. 139-43.
11. Gehrman, P., et al., The relationship between dementia severity and rest/activity circadian rhythms. Neuropsychiatr Dis Treat, 2005. 1(2): p. 155-63.
12. Ancoli-Israel, S., et al., Variations in circadian rhythms of activity, sleep, and light exposure related to dementia in nursing-home patients. Sleep, 1997. 20(1): p. 18-23.
13. Afsar, B., Disruption of circadian blood pressure, heart rate and the impact on glycemic control in type 1 diabetes. Diabetes Metab Syndr, 2015. 9(4): p. 359-63.
14. Cincotta, A.H., et al., Circadian neuroendocrine role in age-related changes in body fat stores and insulin sensitivity of the male Sprague-Dawley rat. Chronobiol Int, 1993. 10(4): p. 244-58.
15. Wang, L. and S. Liangpunsakul, Circadian clock control of hepatic lipid metabolism: role of small heterodimer partner (Shp). J Investig Med, 2016. 64(7): p. 1158-61.
16. Gnocchi, D., et al., Lipids around the Clock: Focus on Circadian Rhythms and Lipid Metabolism. Biology (Basel), 2015. 4(1): p. 104-32.
17. Gerhart Hines, Z., et al., The nuclear receptor Rev-erbα controls circadian thermogenic plasticity. Nature, 2013. 503(7476): p. 410-413.
18. Bookout, A.L., et al., FGF21 regulates metabolism and circadian behavior by acting on the nervous system. Nat Med, 2013. 19(9): p. 1147-52.
19. Shostak, A., J. Meyer-Kovac, and H. Oster, Circadian regulation of lipid mobilization in white adipose tissues. Diabetes, 2013. 62(7): p. 2195-203.
20. Boden, G., et al., Evidence for a circadian rhythm of insulin secretion. Am J Physiol, 1996. 271(2 Pt 1): p. E246-52.
21. Degaute, J.P., et al., Quantitative analysis of the 24-hour blood pressure and heart rate patterns in young men. Hypertension, 1991. 18(2): p. 199-210.
22. Zambon, A.C., et al., Time- and exercise-dependent gene regulation in human skeletal muscle. Genome Biol, 2003. 4(10): p. R61.
23. Carter, R., et al., Non-alcoholic fatty pancreas disease pathogenesis: a role for developmental programming and altered circadian rhythms. PLoS One, 2014. 9(3): p. e89505.
24. Kettner, N.M., et al., Circadian Homeostasis of Liver Metabolism Suppresses Hepatocarcinogenesis. Cancer Cell, 2016. 30(6): p. 909-924.
25. Zhou, D., et al., Evolving roles of circadian rhythms in liver homeostasis and pathology. Oncotarget, 2016. 7(8): p. 8625-39.
26. CDC: Center for Disease Control & Prevention. Retrieved from – https://www.cdc.gov/nchs/fastats/obesity-overweight.htm
27. Menke, A., et al., Prevalence of and Trends in Diabetes Among Adults in the United States, 1988-2012. JAMA, 2015. 314(10): p. 1021-9.
28. Cleator, J., et al., Night eating syndrome: implications for severe obesity. Nutr Diabetes, 2012. 2: p. e44.
29. Gallant, A.R., J. Lundgren, and V. Drapeau, The night-eating syndrome and obesity. Obes Rev, 2012. 13(6): p. 528-36.
30. Colles, S.L., J.B. Dixon, and P.E. O’Brien, Night eating syndrome and nocturnal snacking: association with obesity, binge eating and psychological distress. International Journal of Obesity, 2007. 31(11): p. 1722-1730.
31. Kinsey, A.W., et al., Influence of night-time protein and carbohydrate intake on appetite and cardiometabolic risk in sedentary overweight and obese women. Br J Nutr, 2014. 112(3): p. 320-7.
32. Kalergis, M., et al., Impact of bedtime snack composition on prevention of nocturnal hypoglycemia in adults with type 1 diabetes undergoing intensive insulin management using lispro insulin before meals: a randomized, placebo-controlled, crossover trial. Diabetes Care, 2003. 26(1): p. 9-15.
33. Bo, S., et al., Is the timing of caloric intake associated with variation in diet-induced thermogenesis and in the metabolic pattern? A randomized cross-over study. Int J Obes (Lond), 2015. 39(12): p. 1689-95.
34. Mattson, M.P., et al., Meal frequency and timing in health and disease. Proc Natl Acad Sci U S A, 2014. 111(47): p. 16647-53.

 

 

 

How Modern Light Is Causing Sleep Loss and Making Us SIck | The Paleo Diet

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

How Modern Light Is Causing Sleep Loss and Making Us Sick

LeGates, Tara, Diego Fernandez, and Samer Hattar. “Light as a Central Modulator of Circadian Rhythms, Sleep and Affect.” Nature Reviews Neuroscience. Nature.com, 11 June 2014. Web. 4 May 2015.

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

How Modern Light Is Causing Sleep Loss and Making Us Sick

Kwon, Ilmin, Han Kyoung Choe, Gi Hoon Sun, and Kyungjin Kim. “Mammalian Molecular Clocks.” KoreaMed Synapse. Experimental Neurobiology, 31 Mar. 2011. Web. 4 May 2015.

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

How Modern Light Is Causing Sleep Loss and Making Us Sick

Rahman, Shadab A. et al. “Effects of Filtering Visual Short Wavelengths During Nocturnal Shiftwork on Sleep and Performance.” Chronobiology International 30.8 (2013): 951–962. PMC. Web. 4 May 2015.

Why is the blue light from electronic devices particularly problematic? Quite simply, it suppresses your sleep-related hormone, melatonin, as well as disrupting your body’s 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 ‘sleep quality.’ This means a completely dark bedroom, with no light whatsoever, and also a cool temperature. Cortisol dysregulation is another issue commonly seen in today’s 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 – 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 night’s 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;69:1583–1586.

[15] Moore RY, Lenn NJ. A retinohypothalamic projection in the rat. J Comp Neurol. 1972;146:1–14.

[16] Klein DC, Moore RY, Reppert SM, editors. Suprachiasmatic nucleus: the mind’s clock. New York: Oxford University Press; 1991.

[17] Ralph MR, Foster RG, Davis FC, Menaker M. Transplanted suprachiasmatic nucleus determines circadian period. Science. 1990;247:975–978.

[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: //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.

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