Light, via melanopsin, may exert antidepressant effects through modulation of sleep homeostasis. This statement is:

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Light entering the eye through melanopsin-containing cells sends non-visual signals that help set our internal clock and regulate sleep homeostasis. This means daytime light helps keep circadian timing aligned with the 24-hour day and shapes sleep pressure, which in turn influences mood. Bright, especially morning, light can advance circadian phase and improve sleep timing and quality, factors often linked to better mood.

Clinical evidence supports antidepressant effects from light therapy, particularly in seasonal affective disorder, and to a lesser extent in other depression forms. The mood benefits are thought to arise at least in part from realigning circadian rhythms and modulating sleep pressure, rather than from mood effects isolated from sleep regulation. Since sleep disturbance and circadian misalignment are common in depression, changing sleep homeostasis through light can contribute to antidepressant effects.

Therefore, the statement is true: light, via melanopsin, may exert antidepressant effects through modulation of sleep homeostasis.