Fipna waves are characteristic of REM sleep, while delta waves are characteristic of NREM sleep. Stage one sleep is characterized by relaxed wakefulness, while stage two sleep is characterized by dominant surfers. The SCN produces circadian rhythms by modulating blood pressure and body temperature, rates of action potentials and levels of protein synthesis, action potential velocities, and rates of axonal myelination and dendritic growth. The SCN functions as a third eye in primitive proto-chordates, but in mammals, it influences mood and sleep through the synthesis of oxytocin in the medial forebrain bundle. The anterior septum functions as a third eye in primitive proto-chordates, while vasopressin functions in mammals. The optic chiasm is associated with serotonin, and the pineal gland is associated with melatonin. One of the primary functions of central pattern generators is to produce repetitive rhythmic patterns of movement. They do not cause the pupils to constrict in mammals.