Which of the following statements is true about REM sleep?: (A) It forms 50% of total sleep duration, (B) Sympathetic activity increases, (C) Muscle tone is normal, (D) dreams are not memorized
Answer is B. REM sleep :

It forms 20-25% of total sleep duration
Sympathetic activity increases
Dreams are well memorized
Generalised muscular atony, excpet extraocular muscle, muscles of Penis.