AP PSYCHOLOGY

Detailed explanation-1: -The pineal gland hormone melatonin is released during the biological night and provides the body’s internal biological signal of darkness. Exposure to light both resets the circadian rhythm of melatonin and acutely inhibits melatonin synthesis (1, 2).

Detailed explanation-2: -Your pineal gland releases the highest levels of melatonin when there’s darkness and decreases melatonin production when you’re exposed to light. In other words, you have low levels of melatonin in your blood during the daylight hours and peak levels of melatonin during the nighttime.

Detailed explanation-3: -These findings suggested that daytime bright light increased plasma melatonin production. On the other hand, timed melatonin intake is known to facilitate nocturnal sleep in healthy subjects (3, 42, 47) and improves nocturnal sleep in elderly insomniacs (14, 15).

Detailed explanation-4: -Light exposure is the most important factor related to pineal gland function and melatonin secretion. A single daily light pulse of suitable intensity and duration in otherwise constant darkness is enough to phase shift and to synchronize the melatonin rhythm to 24h (16).

Detailed explanation-5: -Light has two effects on melatonin: day–night light cycles modify the rhythm of its secretion and brief pulses of light of sufficient intensity and duration abruptly suppress its production. The circadian rhythm of pineal melatonin secretion reflects signals originating in the suprachiasmatic nucleus.