• REM sleep's primary function is to reduce the vulnerability caused by N-REM sleep. • REM sleep parameters are directly related to the body’s protection or vulnerability. • REM sleep is cyclic due to its protective function. • REM sleep probably emerged as a brief awakening from N-REM sleep. • REM density is a measure of the organism’s alertness.
Raffael Brito Spinassi (Wed,) studied this question.