0164 EFFECT OF A DAYLIGHT LED VERSUS A CONVENTIONAL LED SOLUTION ON VISUAL COMFORT, DAYTIME ALERTNESS AND SLEEP

Abstract

Conventional LED light sources have a discontinuous light spectrum with a prominent “blue” peak between 450-480nm, which potentially impacts on human circadian physiology and sleep. Thus, we investigated the effects of an advanced LED source simulating the natural daylight spectrum on visual comfort, daytime alertness and sleep. Twelve male young good sleepers spent twice 2.5-days in the laboratory once under a conventional (convLED) and once under a daylight simulating LED (dayLED) condition (16 hours LED exposure during scheduled wakefulness) in a balanced cross over design flanked by a 8-h baseline and a post-light exposure night. The same light settings were used for convLED and dayLED (100 photopic lux at the eye level with a color temperature of 4000K). However, the light spectrum and the color rendering index differed considerably between convLED and dayLED. Subjective visual comfort and sleepiness were continuously rated on conventional scales, and the PSGs were quantified for sleep stages and EEG spectral power density during nonREM sleep. The volunteers rated the light quality of the dayLED as being more pleasant than the convLED (p=0.07). They also felt significantly more alert during the dayLED condition compared to convLED (p<0.01), particularly in the morning/midday hours between 9 and 13h. In comparison to the baseline night, convLED significantly decreased the proportion of NREMS (-4.4 %, p<0.03) at the cost of REM sleep (+5.2%, p<0.004) and reduced EEG power density in the lower spindle frequency range between 11.5- 13.5 Hz (p<0.04), while such changes in sleep were not presented for dayLED. We have preliminary evidence that a daylight LED lighting solution has beneficial effects on visual comfort and daytime alertness and does not affect all-night sleep EEG activity when compared to a conventional LED solution. This study was supported by Toshiba Materials.