The period of REM sleep gets longer as the cycle is repeated during the night where as the time of deep sleep (or quiet sleep) decreases in length.
(The period of REM sleep; gets; longer; T:as the cycle is repeated during the night) (the cycle; is repeated; T:during the night)
The period of REM sleep the cycle
gets is repeated
longer T:as the cycle is repeated during the night
T:during the night