Which one of the following signs will be observed when the patient is on REM sleep?
A. HyperventilationB. Loss of skeletal muscle tone
C. Slow but steady heart rate
D. High amplitude EEG wave
The Answer is B. In a normal
sleep cycle, a person passes through the four stages of slow-wave sleep before
entering REM sleep. In narcolepsy, a person may pass directly from the waking
state to REM sleep. REM sleep is characterized by irregular heart beats and
respiration and by periods of atonia (loss of muscle tone). Hypoventilation is
characteristic of both REM and non-REM sleep because sleep depresses the
central chemoreceptors. Brain activity during REM sleep is higher than during
wakefulness so there is an increase in brain metabolism. It is also the state
of sleep in which dreaming occurs.
