Development and effect analysis of circadian rhythm-assisted LED lighting for reproducing short-wavelength ratio characteristics of natural light

Abstract

The short-wavelength ratio of natural light that changes a day cycle helps maintain the circadian rhythm. The circadian rhythm is a phenomenon in which the flow of physical activity is repeated every 24 hours and is synchronized mainly by natural light. However, since people's exposure time to artificial lighting has increased recently, the issue of circadian rhythm imbalance has been raised, and lighting techniques for reproducing the color temperature or wavelength characteristics of natural light have been proposed. There has not been any case for the short-wavelength ratio cycle reproduction of natural light close to the circadian rhythm; thus, a circadian rhythm-assisted LED light that reproduces the short-wavelength ratio of natural light for one day is presented in this paper, and its effect is confirmed through animal experiment. After the lighting control standard is derived through the analysis of natural light characteristics, its periodic short-wavelength ratio is realized through the control of each LED lighting channel. Subsequently, rat-based animal experiment is conducted to analyze the amount of melatonin, a major factor in circadian rhythm. The results confirm that the proposed lighting environment has higher melatonin levels by about 17% (day7) and 24% (day14) compared with the general lighting environment.