Effect of long-wavelength light on electroencephalogram and subjective alertness

This study extends previous findings on the effect of different levels of short-wavelength light on human alertness. This study explores the alerting ability of long-wavelength light at two levels (40 lx and 160 lx). Eight subjects took part in the 60-minute experiment for each of two nights, during which their objective alertness and subjective alertness were evaluated using electroencephalogram and questionnaire. Results show that both levels increased electroencephalogram beta power, which shows a different pattern compared with the previous findings on short-wavelength light. These results strongly suggest that although short-wavelength light may impact alertness through circadian system, long-wavelength light will have to achieve that through other pathways. The further comparison between current and previous results also suggests that long-wavelength light is just as strong on acute alerting ability, as shown by electroencephalogram measures and self-rating questionnaire, as short-wavelength light.