“Daylight” and Experience (06-26-19)

Cajochen and colleagues investigated the effects of using LEDs that mimic daylight on user experience. They “tested an LED lighting solution mimicking a daylight spectrum. . . . young males twice spent 49 hours in the laboratory under a conventional-LED and under a daylight-LED condition. . . . volunteers had better visual comfort, felt more alert and happier in the morning and evening under daylight LED than conventional LED, while the diurnal melatonin profile, psychomotor vigilance and working memory performance were not significantly different.”  Details on the light sources:   “the spectral composition of the two LED types was different. . . . The blue peak in the conLED was more pronounced at 450 nm as compared to a smoother spectrum of the dayLED. The dayLED had a higher spectral irradiance below 440, between 460 and 520 and over 620 nm, so it was more closely matched to daylight.”

C. Cajochen, M. Freyburger, T. Basishvili, C. Garbazza, F. Rudzik, C. Renz, K. Kobayashi, Y. Shirakawa, O. Stefani, and J. Weibel.  “Effect of Daylight LED on Visual Comfort, Melatonin, Mood, Waking Performance and Sleep.” Lighting Research and Technology, in press, https://doi.org/10.1177/1477153519828419