AP PSYCHOLOGY

Detailed explanation-1: -The suprachiasmatic nucleus (SCN) is a bilateral structure located in the anterior part of the hypothalamus. It is the central pacemaker of the circadian timing system and regulates most circadian rhythms in the body.

Detailed explanation-2: -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.

Detailed explanation-3: -The SCN contain various serotonin (5-HT) receptors. 5-HT input from the midbrain raphe helps to modulate the SCN response to light by regulating phase shifts.

Detailed explanation-4: -The SCN is in a part of the brain called the hypothalamus and receives direct input from the eyes.