Effects of daylight and artificial light on melatonin suppression in educational environment.

An analysis of the characteristics of daylight in a scholastic environment was carried out by comparing SPDs and CCTs of the natural source (sky) during typical winter days with contemporaneous measurements of spectral irradiances and CCTs detected at the eyes level. Data obtained from these measurements together with those detected with artificial light, were used to evaluate the effects on melatonin suppression during the day according to the procedure proposed by Rea et al [2]. Despite illuminances on desks under natural and artificial light corresponded to the EN 12464-1 Standard requirements, the irradiances detected at eye's level, which are essential for melatonin suppression, do not appear to always guarantee the necessary circadian stimulus. Consequently it can be inferred that much care should be devoted in designing lighting systems in educational environments in order to take into account their effects on the human circadian system synchronization.