Does the Reduction of Short-Wavelength Light during the Day Impact Human Sleep

Background: Light is the main synchronizing factor of the circadian system and provides the adaptation of organisms to rhythmic environmental conditions. Exposure to natural daylight ensures the proper functioning of the body, elevated vigilance during the day and better sleep at night. People spend most of the daytime in buildings under artificial lighting with reduced light intensity or a modified natural light spectrum. These conditions can have a negative impact on sleep and work performance. Our study aimed to find out in young healthy individuals (1) the effects of short-wavelength reduction during the daytime on the sleep parameters and (2) to determine the impact of evening intense light exposure depending on previous light history.