Comparison of the Effects of Wavelength and Intensity of Monochromatic Light on Cardiovascular Responses during Task and in Recovery Periods

The purpose of this study was to compare the effects of three different intensities (low, medium, high) of two different wavelengths of light (red and blue) on cardiovascular responses by assessing the responses to an auditory task, and to evaluate the possible correlation between the monochromatic light and the personality traits (anxiety) of subjects. The sessions consisted of 5 minutes of baseline, and 10 minutes of s1-s2 reaction time task during exposure to the red or blue light, with 10-minute recovery periods. As for the results, the influence of wavelength of the monochromatic light was observed in the performance of an auditory task, which revealed that the reaction time for the blue was significantly shorter than that for the red. The influence of intensity of monochromatic light was observed in the blood pressure, especially during the recovery periods, which show that while blood pressure increased up to the medium level of light intensity, it decreased at high intensity. In addition, during the task periods, a significant correlation was found only between change score of mean arterial pressure and changes score of cardiac output, which suggests that under the blue light exposure caused a clear cardiac response. Furthermore, our results suggest that trait anxiety may have an impact on blood pressure responses following lower-irradiance short-wavelength light conditions.