REM, accounting for 20-25% of total sleep, is characterized by high frequency, low amplitude activity that resembles that during wakefulness and rapid eye movements. In this stage, muscles are also paralyzed and body temperature becomes unregulated. Vivid dreams are also often experienced during this stage, and the muscle atonia (paralysis) prevents the sleeper from acting them out.
REM占总睡眠的20至25%，其特点是类似于清醒时的高频率、低振幅的脑波活动以及快速的眼球活动。在这个阶段，肌肉会被麻痹，体温亦会变得不受调节。 REM睡眠中经常会出现生动的梦境，而肌肉麻痹会使睡眠者无法将其行动表现出来。
