Answer
e. REM sleep. REM means ""rapid eye movement. Normally, one descends into this stage about 90 minutes after falling asleep. It is the type of sleep in which dreaming occurs.
Work Step by Step
REM sleep occurs about 90 minutes after one falls asleep In this kind of sleep dreaming occurs. The skeletal muscles are inhibited, but the ocular muscles and the diaphragm are not. The flitting eye movements that characterize this sleep (rapid eye movement sleep) are facilitated by the non-inhibition of the ocular muscles. In REM sleep respiratory rate, heart rate and blood pressure rise. Oxygen usage is also increased, even above the levels of the waking state.
