Beginning of Essay
Theories attempting to explain the origin and functions of REM sleep include: (1) that REM sleep provides stimulation for the development of the brain; (2) that it performs a chemical restoration function, since during REM dreaming neuro-protein synthesis occurs ....

Middle of Essay
.... is caused by internal biological process. Some researchers have proposed the activation-synthesis hypothesis. Their neurological research indicates that large brain cells in the primitive brain stem spontaneously fire about every 90 minutes, sending random stimuli to cortical areas of the BRAIN. As a consequence, memory, sensory, muscle-control, and cognitive areas of the brain are randomly stimulated, resulting in the higher cortical brain attempting to make some sense of it. This, according to the research, gives rise to the experience of a dream. Now, as in the past, the most significant controversy centers on the question of whether dreams ....