[Sleep, learning and memory].

As a subject, "Sleep, Learning and Memory" is quite lively. Many papers have been published on this subject in the last 20 years. However, these papers present major contradictions. This is logic because it is a complex subject and, consquently, without simple solutions. It is important to be precise, as much on a basic as on a clinical experimental level, in a large number of questions. For a correct interpretation of the data it is necessary to sustain a unified vision of human nervous system function. Today we can affirm that, for correct learning and memory processing, a normal and harmonic sleep-wakefulness cycle, including the interphase transition states, is essential. Many findings demonstrate the special and determining role of REM sleep in the mechanisms of memory consolidation.