Daytime Acute Non-Visual Alerting Response in Brain Activity Occurs as a Result of Short- and Long-Wavelengths of Light

Abstract. Very recent preliminary findings concerning the alerting capacities of light stimulus with long-wavelengths suggest the existence of neural pathways other than melatonin suppression that trigger the nonvisual response. Though the nonvisual effects of light during the daytime have not been investigated thoroughly, they are definitely worth investigating. The purpose of the present study is to enrich existing evidence by describing how quantitative electroencephalography (EEG) signal analysis can give insight into the measurement of the acute nonvisual response observed in brain states generated during daytime exposure to light (when melatonin secretion is negligible). EEG changes were assessed in 19 subjects during the daytime while being exposed to both short- (blue, 72 μW/cm2) and long-wavelength (red, 18 μW/cm2) radiation. We showed that artificial light stimulus as low as 40 lux decreases the synchronization in the upper theta, lower alpha, and upper alpha EEG activity spectrum. The direction...