Influence of the spectrum of all-day LED lighting on human daytime and nighttime performance

Indoor LED lighting is directly related to people’s health and performance. This experiment investigated the effect of the spectrum of LED lighting on human daytime and nighttime performance. Six different LEDs were selected for the experiment: ordinary LEDs and daylight LEDs that mimic the full spectrum, with CCTs of 2700K, 4000K, and 5000K for each spectral type (2 spectral types * 3 CCT). A total of 24 subjects participated in the experiment. Each subject was assigned to a specific CCT and experienced two spectral types on different days. Subjects were given a predetermined light exposure for 12 hours a day for each experiment. By analyzing the subjects' performance during the daytime light exposure and nighttime sleep quality after, we found that daytime exposure to light with stronger non-visual stimulus led to higher daytime alertness and better nighttime sleep quality, and the lack of daytime light stimuli led to poor night sleep quality. However, changes in spectral composition within a small range were not enough to cause a sufficiently significantly improve in daily human performance.