Light is a zeitgeber for circadian rhythms.

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Multiple Choice

Light is a zeitgeber for circadian rhythms.

Light acts as a cue that synchronizes the body's internal clock to the day-night cycle. In humans, the brain’s circadian master clock (the SCN) receives light information through specialized retinal cells containing melanopsin, which are especially sensitive to blue light. This signaling helps reset the clock, influencing sleep timing, hormones, and body temperature. The strength of this effect varies with wavelength, intensity, duration, and timing, but light remains the primary driver of circadian entrainment, making the statement true. For example, morning light tends to advance the clock, while evening light can delay it, which explains practices for managing jet lag or shift work.

Light acts as a cue that synchronizes the body's internal clock to the day-night cycle. In humans, the brain’s circadian master clock (the SCN) receives light information through specialized retinal cells containing melanopsin, which are especially sensitive to blue light. This signaling helps reset the clock, influencing sleep timing, hormones, and body temperature. The strength of this effect varies with wavelength, intensity, duration, and timing, but light remains the primary driver of circadian entrainment, making the statement true. For example, morning light tends to advance the clock, while evening light can delay it, which explains practices for managing jet lag or shift work.

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