ABSTRACT
Many literatures and the international lighting companies suggest that light can affect the secretion of cortisol and melatonin via visual and non-visual pathway. Moreover, it also can alter human circadian rhythms. Thanks for the easily-controlled light parameters (e.g., spectrum, correlated color temperature (CCT), color rendering index (CRI), circadian stimulus (CS), etc) of Light-emitting diode (LED) and its energy-saving property, it can provide the proper spectrum to fit the environments and seasons. This study attempted to determine the suitable illumination for evening activities by physiological and psychological assessments. The experimental light source is a RGBW-LED lamp with adjustable light parameters. The experimental light source was the RGBW LED lamp of adjustable lighting parameters, which can produce an LED frequency spectra of three different CS/P values at luminance of 500-lux. In addition, to provide conditions of almost no lighting interference for control, the experiment included a dim light environment (<30-lux). The objective biology data (e.g., heart rate (HR), galvanic skin response (GSR)) and the subjective questionnaire (e.g., heaviness, lightness, etc) from ten participants exposed in different light spectra at environment temperature 25°C 375and the humidity 50% are analyzed. Our results show that CS/P : 0.412 (2700K) light can make human comfortable, increase the time of concentration, and reduce the fidgety feeling and the heavy loading.
