<prompt> Which of the following statements is true about REM sleep?It forms 50 of total sleep durationSympathetic activity increasesMuscle tone is normaldreams are not memorized  <response>: REM sleep :It forms 20-25 of total sleep durationSympathetic activity increasesDreams are well memorizedGeneralised muscular atony, excpet extraocular muscle, muscles of Penis. 