The sleep-wake cycle is ultimately controlled by the part of the brain called the:

A. Optic nerve

B. Suprachiasmatic nucleus

C. Substantia nigra

D. Median forebrain bundle

Answer:- B. Suprachiasmatic nucleus

The correct answer is ‘Suprachiasmatic nucleus.’ The anterior portion of the brain’s hypothalamus contains a bilateral structure known as the suprachiasmatic nucleus, or SCN. Each and every one of the body’s circadian cycles is controlled by the circadian timing system. This structure regulates and controls the sleep-wake cycle.