Research On The Impact Of LED Lighting On Human Pupil And Pulse Non-visual Biological Effects

Lighting has extended from the visual function to the non-visual biological effects, which provides the new research content and methods for the lighting sciences. At the same time, LED, a new type of solid state light source, has bigger advantages compared to the traditional light sources, has been widely used in indoor lighting, road lighting, the headlights and consumer electronics and other fields. So, it is very important to study the impacts of LED light on human non-visual biological effects as the luminescence mechanism of LED is totally different from the traditional light sources.This paper is divided into two parts. The first part is to study the impacts of LED spectrum on pupil contraction rate. In experiment, ten subjects participated in the pupillary light reflex test in different lighting environment with six kinds of LED light with different colors and five kinds of low illumination. The results show that steady pupil contraction rate and recovery pupil contraction rate have a linear relationship under the illumination of 10-70 lx with the correlation coefficient of more than 0.95. In addition, two pupil contraction rates have a linear relationship between circadian factor, which shows that the pupil contraction rate could well represent the degree of non-visual biological effects. Further study the impacts of the spectrum on pupil contraction can provide data and theoretical basis to the research of lighting system based on non-visual biological effects.The second part is to study the impacts of two different dimming methods(Analog and PWM) of LED light on pulse and pupil of human. Two kind of experiments have been conducted. First, the pulse and pupil size of eight subjects have been measured in black environment and white LED light with three levels of color temperature. Second, mix the blue light(464nm, 20lx) to this three levels of color temperature white LED light sources in two different dimming methods to achieve two different lighting environment with the same illumination of 300 lx. The pulse and pupil size of twelve subjects have been tested in this experiment. The results show that the impact of lighting environment created by two dimming methods on pulse change rate and pupil contraction rate have no significantly different; color temperature and illumination of lighting have significant effects on pulse and pupil; adding blue light in testing environment could cause the pulse change rate and pupil contraction rate increases, most notably increase respectively about 6% and 9%. This result is consistent with the present research results. The discussed LED dimming methods and results in this paper can provide data support for LED dynamic lighting.This paper analyzes the change of pupil contraction rate and pulse of human in the non-visual biological effects experiments according to the existing experimental conditions and three types evaluation method of non-visual biological effects, which can provide data and theoretical basis for the study of LED dynamic lighting based on non-visual biological effects.