Acute effects of blue light on alertness

Abstract

The discovery of a third-class retinal photoreceptors (ipRGCs) sensitive to the short wavelength light (from 460nm to 480nm) have influenced research on circadian rhythms over the last two decades, with increasing research focusing on the physiological and psychological effects of blue light and different colour temperatures during both daytime and nighttime. Meanwhile, research on daytime light exposure has given varying results. Piloting an experimental protocol, the acute effects of both monochromatic blue light (max 479 nm) and dim light (<5 lux) were assessed in 12 healthy young subjects, during the morning hours. Chronotype and sleep prior to the test days were also assessed. Participants were exposed to 1 hour dim light (<5 lux) prior to testing for both light conditions. Alertness was measured using a psychomotor vigilance test (PVT) at three different times during the procedure. There was no significant effect of either blue or dim light on alertness, however there was a combined effect of alertness and dim light when total sleep time the night before dim light was accounted for, showing slower response time in the dim light condition.