Artificial Light at Night, Body Clock Disruption, and Breast Cancer Risk in Industrialized Societies

Breast cancer risk may increase due to circadian disruption associated with modern lifestyles.

• Circadian disruption is linked to changes in melatonin production and affects the molecular timing of the circadian clock.
• Stronger endogenous melatonin rhythms are observed in individuals exposed to brighter daytime environments.
• Light intensity required to suppress melatonin at night is decreasing, suggesting increased sensitivity to light.
• Melatonin suppression in animal studies is associated with increased breast tumor development.
• Maintaining a natural day-night light cycle could support healthier melatonin and clock gene expression.
• Exogenous melatonin administration may disrupt circadian rhythms instead of correcting them, depending on the timing of doses.

Simplified