SAD — primary trigger

• A. Increased sunlight exposure in spring
• B. Reduced sunlight exposure in fall/winter
• C. Heat exposure
• D. High humidity

Answer: (B)

Seasonal Affective Disorder is driven by light exposure. When days are shorter and daylight is scarce in fall and winter, the body’s circadian rhythm and mood-regulating systems become less synchronized, often leading to fatigue, sleep problems, and depressive symptoms. Less light means less daytime alertness and higher melatonin activity, which can blunt serotonin function and mood. Because the pattern of SAD typically emerges with reduced daylight and improves when brighter light returns, the primary trigger is reduced sunlight exposure in fall and winter. Increased sunlight in spring tends to alleviate symptoms, while heat exposure or high humidity are not linked to this condition. Bright light therapy can help by compensating for the lack of natural daylight.