Can any doc explain if you dream every time you sleep but just forget it after waking?

Usually : Most people "dream" during their sleep episodes. Dreaming occurs mostly during rapid eye movement sleep (REM). It usually takes 60-90 minutes to get into REM so unless you're sleep deprived (or have a sleep disorder) you have to be asleep for at least that long to have a dream. Studies suggest that we may be more likely to recall the dreams just prior to waking (when most REM happens ).