<prompt> True about REM sleep-Paradoxical sleepSleep spindleDeep sleepSlow eye movement  <response>: Ans. is a i.e., Paradoxical sleep Sleep is basically divided into two phases:-A Non-REM NREM or slow-wave sleep: It is called Non-REM sleep because no rapid eye movement REM is there on eletrooculogram, rather there is slow or quiscent eye movement It is also referred as S-sleep synchronized sleep or quiet sleep or orthodox sleep because there is diminished physiological functions and a low level of overall activity. It is further divided into: -1 Stage 1: It is a transition from wakefulness to sleep and is characterized by disappearance of alpha activity and appearance of theta activity. There is slow eye movements.2 Stage 2: It is characterized by typical EEG activity i.e., Sleep spindles and K-complex. No eye movement occurs.3 Stage 3 4: Stage 3 4 are stages of deep sleep. These are also called slow wave sleep as these stages are characterized by slow delta waves. Delta wave appearance starts in stage 3 and dominated in stage 4.B REM sleep: The REM sleep is so named as there is rapid roving movements of eye, i.e., rapid eye movement REM on electro-oculogram. It is also called paradoxical sleep because there is a paradoxical elevation of brain activity metabolism and physiological activity. The high-amplitude slow waves seen in stage 3,4 of REM sleep is replaced by rapid low voltage activity Beta wave. Features of REM sleep are: -i EEG - Beta-wave, Reappearance of alpha wave, Saw-tooth wave low voltage fast activity, Ponto- genital-occipital spikes.ii Dreamingiii Other features :- Generalized muscular atony, Penile erection, autonomic hyperactivity Increased pulse rate BP, and intermittent movement of small muscle groups. 