How different light colors affect body clock resetting, melatonin reduction, and alertness during brief light exposure

Intermittent 555 nm light pulses induce larger phase delay shifts per minute than continuous exposure.

• Intermittent light exposure is more efficient in resetting the circadian pacemaker compared to continuous exposure.
• A total of 12 healthy young adults participated in the study, receiving different light pulse exposures during the biological night.
• Continuous exposure to 460 nm light resulted in the largest total phase delay shifts, while intermittent exposure to 555 nm light was most effective per minute.
• Melatonin suppression was significantly greater under continuous light exposure compared to intermittent patterns.
• Results suggest a non-linear relationship between light exposure duration and phase resetting responses, influenced by light wavelength.

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