The article reviews the impact of daily changes in characteristics of solar radiation in the circadian region of optical spectrum on diurnal (circadian) activity of human body with changes of solar altitude angle. Analytical expressions, allowing to theoretically estimation instantaneous melatonin content in human blood plasma and dependence of instantaneous human activity during daytime on solar altitude angle, were obtained. 1. The 2017 Nobel Prize in Physiology or Medicine. URL: https://www.nobelprize.org/prizes/medicine/2017/press-release/ (date of reference: 01.10.2020).
2. The Journal of Circadian Rhythms. URL: https://www.jcircadianrhythms.com (date of reference: 01.10.2020).
3. Leonidov Alexander V. Determination of Efficient Modes of Optical Radiation Exposure for Control of Human Circadian Activity // Light & Engineering, 2020, Vol. 28, # 6, pp. 118–126.
4. Alpha and Omega: Brief Handbook [Alfa i omega: kratkiy spravochnik] (Composite authors): trans. from Estonian, Rev. 2, Tallinn: Valgus, 1988, 384 p.
5. Allen, C.W. Astrophysical Quantities (Handbook) [Astrofizicheckiye velichiny (Spravochnik)] / Handbook. Trans. from Eng. Moscow: Mir, 1977, 279 p.
6. Leonidov A.V. Calculation of the Natural Illumination of the Earth’s Surface at Different States of Cloud Cover // Atmospheric and Oceanic Physics, 2019, Vol. 55, # 11, pp. 1592–1601.
7. Meshkov V.V. Basics of Light Engineering: Study Guide for Higher Education Institutions. P. 1 [Osnovy svetotekhniki: ucheb. posobie dlya vuzov. Ch. 1] / Book, 2nd edition, revised. Moscow: Energiya, 1979, 368 p.
8. Leonidov A.V. Changes in the natural irradiance and illumination of the earth’s surface during the 11 – year cycle of solar activity // Light & Engineering, 2020, Vol. 28, # 2, pp. 61–66.
9. Leonidov A.V. On Optical Receivers in the Pathway Implicated in Regulating the Human Circadian Rhythm // Biophysics, 2016, Vol. 61, # 6, pp. 1001–1010.
10. Brainard G.C., Glickman G.L. The biological potency of light in humans: significance to health and behavior / CIE152: 2003 “Proc. 25th Sess. CIE, San Diego”, 2003, pp. I‑22–I‑33.
11. Brainard, G.K., Glickman, G.L. Biological Effect of Light on Human Health and Behaviour [Biologicheskoye vliyaniye sveta na zdorovye i povedeniye cheloveka] // Svetotekhnika, 2004, # 1, pp. 4–8.
12. Thapan K., Arendt J., Skene D.J. An action spectrum for melatonin suppression: evidence for a novel non – rod, non – cone photoreceptor system in humans // J. Physiol. 2001, Vol. 535, pp. 261–267.
13. Brainard G.C., Provencio I. Photoreception for the neurobehavioral effects of light in humans / CIE031:2006 Proc. 2nd CIE Expert Symposium on “Lighting and Health”, pp. 6–21.
14. Leonidov A.V. Spectral selective transformations of solar radiation by retinal photoreceptors in the control of the circadian rhythm of the human body throughout an 11 – year cycle of solar activity // Biophysics, 2020, Vol. 65, # 3, pp. 515–522.
15. Leonidov A.V. Approximation of relative spectral sensitivity function of retina receptors // Light & Engineering, 2011, Vol. 19, # 1, pp. 49–51.
16. Leonidov A.V. About analytical presentation of relative spectral luminous efficiency function // Light & Engineering, 2012, Vol. 20, # 4, pp. 13–15.
17. Kovalzon V.M. Melatonin without Miracles [Melatonin bez chudes] // Priroda, 2004, Vol. 2, pp. 12–19.

• Previous article
• Next article

• the Sun
• Solar altitude angle
• transmittance
• direct and diffused radiation
• spectral range
• melatonin
• concentration
• change rate
• circadian activity