What is dreaming?

Dreaming is an involuntary mental process which produces a reworking of information stored in memory, usually associated with experiences of the dreamer the day before. The dream takes us into a virtual reality made up of images, sounds, thoughts and / or feelings. Memories that are kept on waking may be simple (a picture, sound, idea, etc..) Or very elaborate.

The most elaborate dreams contain scenes, characters, scenes and objects. There is evidence that may have dreams in any of the stages of human sleep. However, remember more dreams and the dreams are more elaborate in what is called REM (Rapid Eye Movement, for its acronym in English Rapid Eye Movement) which takes place on the last leg of the sleep cycle.


That is the act of dreaming that has been confirmed only in Homo sapiens. Some animals also go through REM sleep, but their subjective experience is difficult to determine. It seems that the mammals are the animals most likely to dream because their sleep cycle similar to humans. The animal that spends more time in REM sleep is the armadillo.

In many cultures predictive value is attributed to the dream, conceived as an encrypted message that is necessary to unravel. We find this belief, for example, in the Bible (where Joseph interprets Pharaoh's dreams). In the early twentieth century, Sigmund Freud takes up the issue from a rational perspective in his Interpretation of Dreams (1900). The analysis of them is for him the access via regia to the unconscious.

The reason for the dreams:

The hypothesis that sleep participates in the consolidation of recent memory has been investigated by four paradigms:
Effects of sleep deprivation on the consolidation of memories;
Effects of learning on post-training sleep;
Effects of stimulation during sleep on sleep patterns and memory, and
Re-expression of specific neural patterns during post-training sleep.

Dream studies confirm convincingly the idea that sleep is deeply involved in memory functions in humans and animals. However, the available data are still too few to confirm or reject the hypothesis recently exposed unequivocally that the consolidation of non-declarative memories and statements regarding processes depend on REM and NREM.