Effects of calibrated blue–yellow changes in light on the human circadian clock

This study tested the impact of different light color changes on the human circadian system and sleep quality using precise, controlled light conditions. Sixteen participants were exposed to three light settings (baseline, blue-dim, yellow-bright) for one hour at night. Results showed no significant differences in melatonin suppression, sleep onset, or quality among the light settings, suggesting that light color changes alone are not major influencers of the circadian clock under typical room lighting. Melanopsin, a light-sensitive pigment, was reaffirmed as the primary driver of circadian responses, not cone-specific color vision pathways.

To minimize circadian disruption, prioritize reducing overall light intensity, especially short-wavelength (blue) light, in the evening rather than focusing on light color shifts. Utilize screen filters or dim light settings before bed. This recommendation aligns with evidence prioritizing melanopsin's role in circadian regulation, but individual sensitivity to light remains a factor for tailored approaches.