REM rebound involves the: tendency for REM sleep periods to become increasingly longer…

REM rebound involves the:
tendency for REM sleep periods to become increasingly longer and more frequent as a normal night of sleep progresses.
increase in REM sleep that characteristically follows intense learning episodes or stressful daytime experiences.
unusual symptoms of tiredness and irritability that follow periods of REM sleep deprivation.
tendency for REM sleep to increase following REM sleep deprivation.