PSYCHOLOGY OF EMOTIONS

Detailed explanation-1: -The suprachiasmatic nucleus, via an inhibitory projection to the paraventricular nucleus of the hypothalamus, controls the sympathetic output to the pineal gland that is responsible for melatonin secretion. This pathway is responsible for the peak of melatonin secretion during darkness.

Detailed explanation-2: -Efferent projections from the suprachiasmatic nucleus innervate structures such as the pineal gland, producing melatonin during the night for induction of sleep.

Detailed explanation-3: -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-4: -C. The suprachiasmatic nucleus signals the pineal gland, which in turn secretes the hormone melatonin.

Detailed explanation-5: -In the brain, a small group of hypothalamic nerve cells, the suprachiasmatic nucleus (SCN), functions as a master circadian pacemaker controlling the timing of the sleep-wake cycle and coordinating this with circadian rhythms in other brain areas and other tissues to enhance behavioral adaptation.