One common feature has been noticed about the recollection of dreams. Most persons awakened more than about ten minutes after the REMs have ceased are unable to recall their dreams. The rapid loss of memory of a dream is among the most astonishing aspects of the whole subject. It is as if the state of wakefulness instantly sweeps away the delicate cobwebs that constitute the dream fabric. Since actual events that have occurred ten hours previously can be can be distinctly recalled by anyone, it is curious that a vivid dream only ten minutes old should vanish so utterly and without trace. In fact, a dreamer can wake up in the morning with the last dream still on his mind, yet between waking up and getting out of bed, his dream may be lost beyond recall.
It has been suggested that we have a dream memory which differs from the waking memory, and that some part of ourselves comes into operation during the dream-state that is only tenuously linked with the conscious mind.
(Cavendish, 1974, p. 79).