Natural Light Property-Based LED Lighting System to Maintain Human Circadian Rhythm

Abstract

The cyclic properties of natural light give an effect on human health, and the intensity and wavelength of natural light are known to be important factors to maintain human circadian rhythm. However, modern people who stay longer indoors are exposed to the fixed light environment of artificial lighting, resulting in circadian rhythm imbalance and subsequent sleep disturbances. In this paper, a LED lighting system that reproduces the natural light properties with day cycle is proposed to support the human circadian rhythm. To do this, the properties of natural light that keep changing were measured and analyzed every hour, and then the color temperature and wavelength ratio of natural light over time were reproduced by controlling each channel of LED lighting. In order to confirm the effect of the proposed lighting that supports maintaining a circadian rhythm, a confirmation experiment of melatonin change in the animal body was performed. The experimental results showed that the rats irradiated with the proposed lighting had an increased melatonin level by more than around 20ng/ml compared to the rats irradiated with the general lighting, thus confirming that the proposed lighting had a positive effect on sustaining the circadian rhythm.