Genetic progress in eye research: how light-sensitive retinal cells help regulate daily body rhythms

Melanopsin-expressing retinal ganglion cells (ipRGCs) are integral to synchronizing human biology with the 24-hour day-night cycle.

• Light-dark cycles are the main environmental cues that help organisms align their internal biological processes with the 24-hour cycle.
• ipRGCs transmit signals to the body's master biological clock, the suprachiasmatic nuclei (SCN), through the retinohypothalamic tract.
• The retina exhibits its own circadian rhythms, which include daily changes in visual sensitivity and neurotransmitter levels.
• Both central and peripheral biological clocks operate on a similar molecular mechanism that follows a circadian rhythm of about 24 hours.

Simplified