Dream.

A dream is a succession of images, ideas , emotions, and
sensations that usually occur involuntarily in the mind
during certain stages of sleep . Opinions about the meaning of dreams have varied and
shifted through time and culture. Many endorse the Freudian
theory of dreams – that dreams reveal insight into hidden
desires and emotions. Other prominent theories include
those suggesting that dreams assist in memory formation,
problem solving, or simply are a product of random brain
activation. he content and purpose
of dreams are not fully understood, though they have been
a topic of scientific speculation, as well as a subject of
philosophical and religious interest, throughout recorded
history. Dream interpretation is the attempt at drawing
meaning from dreams and searching for an underlying
message. The scientific study of dreams is called
oneirology.
Dreams mainly occur in the rapid-eye movement (REM)
stage of sleep —when brain activity is high and resembles
that of being awake. REM sleep is revealed by continuous
movements of the eyes during sleep. At times, dreams may
occur during other stages of sleep. However, these dreams
tend to be much less vivid or memorable. The length of a
dream can vary; they may last for a few seconds, or
approximately 20–30 minutes. People are more likely to
remember the dream if they are awakened during the REM
phase. The average person has three to five dreams per
night, and some may have up to seven; [4] however, most
dreams are immediately or quickly forgotten. Dreams tend
to last longer as the night progresses. During a full eight-
hour night sleep, most dreams occur in the typical two
hours of REM. Opinions about the meaning of dreams have varied and
shifted through time and culture. Many endorse the Freudian
theory of dreams – that dreams reveal insight into hidden
desires and emotions. Other prominent theories include
those suggesting that dreams assist in memory formation,
problem solving, or simply are a product of random brain
activation.