The neural structures that regulate sleep and wakefulness are primarily the reticular formation of the brainstem. This reticular formation consists of the superior reticular activating system in the superior pontocerebrum and the superior reticular inhibiting system in the inferior pontocerebrum, both of which act simultaneously to regulate the cycles of sleep and wakefulness. The superior reticular activation system is more important, as it governs wakefulness. This activation system is physiologically complex, with a variety of neurons and multiple synapses. It can transmit various stimuli from various parts of the body, including internal and external stimuli, to the neurons in the cerebral cortex in a broad and synchronized manner, maintaining the state of arousal in the cerebral cortex. This upward impulse from the reticular formation is capable of eliciting the waking response. In addition to maintaining consciousness, it is also involved in the integration of various sensory and motor activities in the internal organs. If the reticular superior structural system is damaged, it may cause drowsiness, lethargy, or even coma.