Memory and Sleep
Memory and Sleep(dreams)
As studies of sleep learning as well as studies of so-called nondreamers have shown, the memory-recording processes of the brain seem to be switched off during sleep. In so-called nondreamers who, it has been demonstrated, actually do dream—this memory shutdown is simply more complete than it is for the rest of the population. Even people who remember their dreams every night only remember the last several dreams they had immediately before awakening. Dreams from the early and middle periods of sleep are permanently forgotten.
It has been hypothesized that dreams are easily forgotten because they are so incoherent. Another theory is that dreams are quickly forgotten because they contain repressed material that the conscious mind does not wish to remember. However, although these two factors probably do account for some forgetting, they are inadequate for explaining the extensive loss of dream content that occurs every morning upon awakening. The precise process has yet to be discovered, but there is almost certainly some sort of neurochemical mechanism that shuts down memory during sleep.