This article is from the Dreaming FAQ, by "Lars Rune Foleide" larsrune@sf.telia.no .
Yes. All humans (and mammals) have REM (Rapid Eye Movement) sleep. The
most vivid dreaming occurs in REM-sleep. You start a new REM phase
roughly every 90-minute throughout the whole night with increasing
duration. But all this can change depending on what you eat, if you
are on drugs, or if you have missed your REM sleep for some
reason. People stopping with REM deprivation drugs will experience a
REM rebound. So you dream a lot during the night, and most of your
dreams are forgotten. If you don't pay attention to them and only
sleep a few hours you most likely will not remember any dream at
all. Dreaming in non-REM tends to be more thought-like.
 
Continue to: