The science of circadian alignment
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Time to read 6 min
What is the circadian rhythm?
The circadian rhythm is your body's natural internal clock.
It regulates almost every system in your body, from your sleep-wake cycle to your cardio, metabolic, and immune systems.
"Circadian" is derived from the latin words circa and dian which translate to "roughly a day" because your circadian rhythm is approximately 24-hours.
Your circadian rhythm relies on light and darkness to synchronise with Earth's day-night cycle.
What is circadian disruption?
When your circadian rhythm (think body clock) drifts out of sync with the day-night cycle, it's what researchers call circadian disruption. Although night-shift workers are at the greatest risk, it's estimated almost 90% of day-time workers suffer a milder form of circadian disruption.1 This is a consequence of poor indoor lighting and lack of sunlight exposure, as shown by extensive research.
Since practically all bodily functions are influenced by the internal clock, chronic circadian disruption has far-reaching consequences. In the short term, you may feel sleepy or groggy during the day and struggle to sleep at night. Chronic circadian disruption correlates with higher rates of heart disease, cancer, cognitive diseases like Alzheimer's, and metabolic conditions such as diabetes. Together, these four conditions kill 80% of adults over fifty in industrialised countries.
Check if your circadian rhythm is aligned with our free quiz.
The dark side of artificial light
Your circadian rhythm (sleep-wake cycles) is regulated by special light-sensitive cells in our eyes called intrinsically photosensitive retinal ganglion cells (ipRGCs). These ipRGCs are only sensitive to a fraction of the visible spectrum, speaking at 480nm. We call this light blue-sky light because visually it looks like the colour of a blue sky.
Scientists agree that we need a minimum of 250 melanopic effective daylight illuminance (m-EDI) during the day to set the circadian rhythm2. However, seated at a typical desk without window light, you're exposed to roughly half that level. That's because modern LEDs emit little blue-sky light, meaning that although they may appear bright, they have little effect on the circadian rhythm. If you spend much of your day below this minimum threshold—such as by working indoors—your internal circadian clock can become desynchronized from the natural 24-hour day/night cycle.
How circadian lighting helps
Circadian lighting works by raising the m-EDI indoors to ensure proper circadian timing. We're making circadian lighting more accessible with the goal of ending circadian disruption.
Introducing Loop, a personal circadian light. Loop supplements your existing lighting—filling the blue-sky dip—to bring any office up to 250+ m-EDI. At night, Loop dynamically transitions to a <10 m-EDI light, in line with evidence based recommendations.
Results
Many Loop users report feeling more focused and alert during the day and sleeping better at night. Additionally, some report a reduction in sub-clinical seasonal affective disorder (SAD). Their experiences are corroborated by a growing body of research demonstrating the benefits of light tuned to support a healthy circadian rhythm.
During the day, blue-enriched light has been shown to:
• Improve alertness and cognitive performance.3
• Improve mood.4
• Alleviate sub-clinical seasonal affective disorder.5
• Promote melatonin production.6
• Help you fall asleep faster.7
• Enhance sleep quality.8
• Help you stay asleep longer.8
Additionally, supporting an aligned circadian rhythm promotes a longer and healthier life by:
• Reducing the risk of heart disease.9
• Reducing the risk of cancer.10
• Reduce the risk of obesity.11
• Reduce the risk of diabetes.12
• Reduce risk of neurodegenerative diseases.13
• Reduce the risk of depression and other mental health conditions.14
"While completing my doctoral thesis (neuroscience of vision), my school gave me an office conveniently located close to my house, but with very little natural light! I worked long hours and found my circadian rhythm out of wack with day and night. I was thrilled to hear of an NZ-made product that understood the science of how visual pathways set the pace of alertness and sleep. Within days, Osin boosted my productivity and health, with a firm burst of blue light in the mornings that transitioned to orange in the evenings. My sleep improved and I found myself more focused during the days. It doesn't hurt that it's a beautiful product - I had the coolest looking desk in the lab!"
Safety
There's a mistaken belief that all blue light is harmful. Blue light can be divided into two bands: blue-violet light (415-455 nm) and blue-sky light (465-495 nm). The two bands mentioned above exhibit vastly effects effects on the eyes.
Several studies have been published in medical literature demonstrating that blue-violet light can induce retinal cell death at high intensities; however, scientists still disagree whether this is a risk at the lower intensities we are routinely exposed to from devices.
On the other hand, the Osin Loop only emits blue-sky light, which in addition to being widely regarded as safe, is critical for aligning our circadian rhythms, which in turn maintain and regulate our sleep, mood and many other biological functions.
References
[1] Roenneberg, T., & Merrow, M. (2016). The Circadian Clock and Human Health. Current biology : CB, 26(10), R432–R443. https://doi.org/10.1016/j.cub.2016.04.011
[2] Brown, T. M., Brainard, G. C., Cajochen, C., Czeisler, C. A., Hanifin, J. P., Lockley, S. W., Lucas, R. J., Münch, M., O'Hagan, J. B., Peirson, S. N., Price, L. L. A., Roenneberg, T., Schlangen, L. J. M., Skene, D. J., Spitschan, M., Vetter, C., Zee, P. C., & Wright, K. P., Jr (2022). Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults. PLoS biology, 20(3), e3001571. https://doi.org/10.1371/journal.pbio.3001571
[3] Boubekri M, Lee J, MacNaughton P, Woo M, Schuyler L, Tinianov B, Satish U. The Impact of Optimized Daylight and Views on the Sleep Duration and Cognitive Performance of Office Workers. International Journal of Environmental Research and Public Health. 2020; 17(9):3219. https://doi.org/10.3390/ijerph17093219
Viola, A. U., James, L. M., Schlangen, L. J., & Dijk, D.-J. (2008). Blue-enriched white light in the workplace improves self-reported alertness, performance and sleep quality. Scandinavian Journal of Work, Environment & Health, 4, 297–306. https://doi.org/10.5271/sjweh.1268
[4] Mills, P. R., Tomkins, S. C., & Schlangen, L. J. (2007). The effect of high correlated colour temperature office lighting on employee wellbeing and work performance. Journal of Circadian Rhythms, 5(0), Art. 2.DOI: https://doi.org/10.1186/1740-3391-5-2
[5] Meesters, Y., Winthorst, W. H., Duijzer, W. B., & Hommes, V. (2016). The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder. BMC Psychiatry, 16(1), 27. https://doi.org/10.1186/s12888-016-0729-5
[6] Hébert, M., Martin, S.K., Lee, C. and Eastman, C.I. (2002), The effects of prior light history on the suppression of melatonin by light in humans. Journal of Pineal Research, 33: 198-203. https://doi.org/10.1034/j.1600-079X.2002.01885.x
te Kulve, M., Schlangen, L. J. M., & van Marken Lichtenbelt, W. D. (2019). Early evening light mitigates sleep compromising physiological and alerting responses to subsequent late evening light. Scientific Reports, 9(1), 16064. https://doi.org/10.1038/s41598-019-52352-w
[7] Li D, Fang P, Liu H, Chen L, Fu Y, Liu J, Xie B, Liu Y, Ye H, Gu P. The Clinical Effect of Blue Light Therapy on Patients with Delayed Sleep-Wake Phase Disorder. Nat Sci Sleep. 2022;14:75-82 https://doi.org/10.2147/NSS.S344616
[8] Boubekri, M., Lee, J., MacNaughton, P., Woo, M., Schuyler, L., Tinianov, B., & Satish, U. (2020). The Impact of Optimized Daylight and Views on the Sleep Duration and Cognitive Performance of Office Workers. International Journal of Environmental Research and Public Health, 17(9). https://doi.org/10.3390/ijerph17093219
Li D, Fang P, Liu H, Chen L, Fu Y, Liu J, Xie B, Liu Y, Ye H, Gu P. The Clinical Effect of Blue Light Therapy on Patients with Delayed Sleep-Wake Phase Disorder. Nat Sci Sleep. 2022;14:75-82 https://doi.org/10.2147/NSS.S344616
[9] Reutrakul, S., & Knutson, K. L. (2015). Consequences of Circadian Disruption on Cardiometabolic Health. Science of Circadian Rhythms, 10(4), 455–468. https://doi.org/10.1016/j.jsmc.2015.07.005
Wong, P. M., Hasler, B. P., Kamarck, T. W., Muldoon, M. F., & Manuck, S. B. (2015). Social Jetlag, Chronotype, and Cardiometabolic Risk. The Journal of Clinical Endocrinology & Metabolism, 100(12), 4612–4620. https://doi.org/10.1210/jc.2015-2923
[10] Gery, S., & Koeffler, H. P. (2010). Circadian rhythms and cancer. Cell Cycle, 9(6), 1097–1103. https://doi.org/10.4161/cc.9.6.11046
Masri, S., & Sassone-Corsi, P. (2018). The emerging link between cancer, metabolism, and circadian rhythms. Nature medicine, 24(12), 1795–1803. https://doi.org/10.1038/s41591-018-0271-8
[11] Reutrakul, S., & Knutson, K. L. (2015). Consequences of Circadian Disruption on Cardiometabolic Health. Science of Circadian Rhythms, 10(4), 455–468. https://doi.org/10.1016/j.jsmc.2015.07.005
Roenneberg, T., Allebrandt, K. V., Merrow, M., & Vetter, C. (2012). Social Jetlag and Obesity. Current Biology, 22(10), 939–943. https://doi.org/10.1016/j.cub.2012.03.038
[12] Reutrakul, S., & Knutson, K. L. (2015). Consequences of Circadian Disruption on Cardiometabolic Health. Science of Circadian Rhythms, 10(4), 455–468. https://doi.org/10.1016/j.jsmc.2015.07.005
Wong, P. M., Hasler, B. P., Kamarck, T. W., Muldoon, M. F., & Manuck, S. B. (2015). Social Jetlag, Chronotype, and Cardiometabolic Risk. The Journal of Clinical Endocrinology & Metabolism, 100(12), 4612–4620. https://doi.org/10.1210/jc.2015-2923
[13] Logan, R. W., & McClung, C. A. (2019). Rhythms of life: Circadian disruption and brain disorders across the lifespan. Nature Reviews Neuroscience, 20(1), 49–65. https://doi.org/10.1038/s41583-018-0088-y
Videnovic, A., & Zee, P. C. (2015). Consequences of Circadian Disruption on Neurologic Health. Sleep medicine clinics, 10(4), 469–480. https://doi.org/10.1016/j.jsmc.2015.08.004
[14] Burns, A. C., Windred, D. P., Rutter, M. K., Olivier, P., Vetter, C., Saxena, R., Lane, J. M., Phillips, A. J. K., & Cain, S. W. (2023). Day and night light exposure are associated with psychiatric disorders: An objective light study in >85,000 people. Nature Mental Health, 1(11), 853–862. https://doi.org/10.1038/s44220-023-00135-8