Evidence is quickly mounting that individuals who have diabetes may improve their glucose levels by tightly regulating their exposure to light.
Do Not Let Your Light Shine!
More than 450 million people worldwide have diabetes. In America alone, 85 million Americans have prediabetes. The use of light at inappropriate times is one of the major culprits that promotes this pandemic of obesity and diabetes. Think of your body has being a massive orchestra that ideally coordinates its string, wind, and brass sections in rhythm to thousands of body clocks. What happens to classical music when a whole section of the orchestra misses its entrance or jumps in prematurely with the wrong notes? Dysfunctional discord usurps wonderful melodies. Feeling out of tune?
Evening Light Exposure Impacts Appetite and Weight
Recent research indicates that exposure to blue-enriched light from electronic devices immediately before and during evening meals may increase hunger and alter metabolism. Blue light exposure in one study, when compared to dim light, was linked to an increase in hunger that began 15 minutes after light onset and persisted almost two hours after the meal. In this study, blue light exposure also decreased sleepiness and resulted in higher measures of insulin resistance.1 In other words, individuals who eat in the evening while being exposed to high levels of blue light have higher blood glucose and less insulin response.
A minimal exposure of light during night hours can make it more difficult to control blood sugar. Even a single night of exposure to light will mess up glucose metabolism!2
Blue Light Impairs Insulin Sensitivity
The timing of our bodies to light greatly affects how our bodies respond to insulin! You see, just a small exposure to light at night can profoundly affect insulin sensitivity or the ability of your muscle cells to respond to insulin.
Studies from the University of Geneva show that people exposed to light at the wrong time — workers in shift patterns or checking cell phones and tablets in the middle of the night, for example — are more likely to develop metabolic diseases such as obesity and diabetes.3,4 Disturbed circadian rhythm and exposure to light at the wrong time compromises the gut, the pancreas, and the liver—three organs vital to good glucose control and efficient metabolism.5
Damage to the retina is one of the long-term complications of diabetes. Even periodic exposure to blue light causes retinal damage in animals. It might be prudent for those who have diabetes to put a blue light protective filter on their mobile devices and computer screens or get some blue light filter glasses for the late afternoon and evening use. Better yet, get your blue light from the sunshine earlier in the day when it is more beneficial!6
Exposure to blue light in the evening significantly decreases melatonin production and the quality of sleep.7 Melatonin is a hormone that promotes sleep, protects us from inflammation, and discourages undesirable clotting. Poor sleep quality in people with diabetes reduces their ability to control their blood sugar levels successfully!8 Additionally, defective sleep quality encourages inflammation that consequentially pushes diabetic complications.9
Right Timing of Light Helps
Sunshine and even the right timing of blue light therapy have their therapeutic benefits! Blue light hastens the relaxation process after acute psychosocial stress10 and has been effective against certain antibiotic resistance organisms.11
Several studies show that increasing exposure to bright sunlight lowers the risk for type 2 diabetes; lowers the risk for heart disease by lowering blood insulin and lipid levels; and increases vitamin D levels.12,13 More exposure to sunlight has been linked to less insulin resistance, improved beta-cell functioning, and lower triglycerides (blood fats).14
The timing of exposure to moderate levels of light may influence body mass index (BMI) and body fat. People who received the majority of their bright light in the morning did weigh less than those who were exposed to most of their bright light after 12 p.m.15
Healthy individuals, in another study, who received more exposure to moderate or higher intensity light earlier in the day, had lower body mass index and percent body fat than those with more of their moderate or higher intensity light exposure later in the day.16
Yes, indeed, insulin sensitivity does vary with time of day and an individual’s circadian rhythm. Here are some enlightening tips if you have diabetes or the risk for developing it.
- Cultivate regularity in schedule. Try to get a job with regular hours!
- Get exposure to bright light, preferably sunlight, especially in the morning! Sunlight will improve your mood and blood sugar.
- Avoid the intense sunlight hours in the summer between 11 am to 3 pm. Apply a natural, mineral based type sunscreen and wear a broad rim hat to avoid sunburn.
- Cover your eyes with a dark, comfortable bandanna if you have to sleep with a night light on or if street lights shine through your blinds.
- Avoid reading from a computer or tablet at least two hours prior to your retirement or wear blue light filtered glasses.
- Seriously, avoid shift work or limit it! A low fat diet on days you have to perform shift work will help ameliorate some of the negative effects of disturbed circadian rhythm.
- If you are taking insulin or a diabetic medicine, talk with your physician about what is the best time to take it when your schedule is irregular.
Conclusions: Remember darkness at night is essential to your health! The right timing of light exposure will improve your blood sugar level. Even a minimal exposure of light during night hours can sabotage your efforts to prevent or control diabetes. As important as light is in managing diabetes, there are many science-validated natural remedies to improve blood sugar control! Check out our referenced articles for more ways you can improve prediabetes and diabetes naturally at Diabetes Endocrine Health.
Disclaimer: The information in this article is helpful and is educational. It is not the author’s or authors’ or Wildwood Health Institute’s intent to substitute the blog article for diagnosis, counseling, or treatment by a qualified health professional.
Copyright through December 2023. All rights reserved by Wildwood Sanitarium, Inc.
- Cheung, Ivy. Morning and Evening Blue-Enriched Light Exposure Alters Metabolic Function in Normal Weight Adults. PLOS ONE, 2016; 11 (5): e0155601 DOI: 10.1371/journal.pone.0155601.
- American Academy of Sleep Medicine. “Light exposure during sleep may increase insulin resistance: Chronic overnight light exposure could have long-term effects on metabolic function.” ScienceDaily. 4 June 2018. www.sciencedaily.com/releases/2018/06/180604172736.htm.
- Aras, Ebru. Et al. Light Entrains Diurnal Changes in Insulin Sensitivity of Skeletal Muscle via Ventromedial Hypothalamic Neurons. Cell Reports, 2019; 27 (8): 2385 DOI: 10.1016/j.celrep.2019.04.093.
- University of Granada. “Blue lighting is scientifically proven to help us relax faster than white lighting after an argument.” ScienceDaily., 10 November 2017. www.sciencedaily.com/releases/2017/11/171110113936.htm.
- Skene DJ. el al., “Separation of circadian- and behavior-driven metabolite rhythms in humans provides a window on peripheral oscillators and metabolism,” PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1801183115
- Lin CH. Editor’s Highlight: Periodic Exposure to Smartphone-Mimic Low-Luminance Blue Light Induces Retina Damage Through Bcl-2/BAX-Dependent Apoptosis. Toxicol Sci. 2017 May 1;157(1):196-210. doi: 10.1093/toxsci/kfx030.
- Blue light has a dark side. Harvard Health Letter. www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side. May 2012
- Knutson KL. Cross-Sectional Associations Between Measures of Sleep and Markers of Glucose Metabolism Among Subjects With and Without Diabetes: The Coronary Artery Risk Development in Young Adults (CARDIA) Sleep Study. Diabetes Care, 2011; 34 (5): 1171 DOI: 10.2337/dc10-1962.
- Emory University. “Poor sleep quality increases inflammation, community study finds.” ScienceDaily. 15 November 2010. www.sciencedaily.com/releases/2010/11/101114161939.htm.
- Minguillon J. Blue lighting accelerates post-stress relaxation: Results of a preliminary study. PLOS ONE, 2017; 12 (10): e0186399 DOI: 10.1371/journal.pone.0186399
- Liebert M. Inc./Genetic Engineering News. “Blue Light Destroys Antibiotic-resistant Staph Infection.” ScienceDaily. 31 January 2009. www.sciencedaily.com/releases/2009/01/090129131839.htm.
- Shore-Lorenti C, Brennan SL, Sanders KM, Neale RE, Lucas RM, EbelingPR.Shining the light on Sunshine: a systematic review of the influence of sun exposure on type 2 diabetes mellitus-related outcomes. Clin Endocrinol (Oxf). 2014 Dec;81(6):799-811.
- Lindqvist PG, Olsson H, Landin-Olsson M. Are active sun exposure habits related to lowering risk of type 2 diabetes mellitus in women, a prospective cohort study? Diabetes Res Clin Pract. 2010 Oct;90(1):109-14.
- Noordam R, et al. Bright sunlight Exposure May Decrease the Risk for Diabetes and CVD. J Clin Endocrinol Metab. 2019;doi:10.1210/jc.2018-02532. .February 19, 2019
- Northwestern University. “Bright light alters metabolism.” ScienceDaily. 18 May 2016. www.sciencedaily.com/releases/2016/05/160518141416.htm.
- American Academy of Sleep Medicine. “Mean light timing may influence body mass index, body fat.” ScienceDaily. 9 June 2015. www.sciencedaily.com/releases/2015/06/150609121956.htm.