Alerting effects of short-wavelength (blue) and long-wavelength (red) lights in the afternoon

Exposure to red light significantly lowers brain wave activity associated with relaxation during the afternoon.

• 48-minute exposures to red light resulted in significantly lower brain power in the alpha, alpha-theta, and theta ranges compared to darkness.
• Exposure to blue light also reduced alpha and alpha-theta power, but these changes were not statistically significant.
• The findings indicate that light exposure can enhance alertness in the afternoon, particularly during the post-lunch dip hours.
• These results suggest that the alerting effects of light do not necessarily require suppression of melatonin.

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