What hormone is primarily affected by light exposure?

• A. Cortisol
• B. Melatonin
• C. Adrenaline
• D. Insulin

Answer: (B)

Melatonin is the hormone primarily influenced by light exposure. It is produced by the pineal gland in the brain and plays a crucial role in regulating sleep-wake cycles, also known as circadian rhythms. Melatonin production is stimulated by darkness and inhibited by light. When exposed to light, particularly blue light, the production of melatonin decreases, leading to increased alertness and wakefulness. This natural response is essential for adjusting sleep patterns based on the time of day.

Understanding this relationship is vital for recognizing the importance of light exposure in sleep hygiene and the effects of artificial light on health. Other hormones, such as cortisol, adrenaline, and insulin, are influenced by various factors like stress and metabolic needs rather than direct light exposure, making melatonin the primary hormone affected by light conditions.