Dreams are a form of cognitive activity that occur during sleep. Like vivid memories and daytime fantasies, dreams involve visual images in the absence of external visual stimulation. Some dreams are so realistic and well organized that we feel as though they must be real-- that we simply cannot be dreaming this time.
Dreaming has always been the subject of controversy. Egyptian papyrus documents dating back to 2000 BC discuss dreams and their interpretations. In ancient Greece the dreamer was believed to be in contact with the gods.
In 1900, Sigmund Freud ushered in the modern age of dream research in his monumentally original book The Interpretation of dreams. According to Freud, dreams have a meaning which can be deciphered if one looks deeply enough. In his view, the dreams concerns the dreamers past and present, and it arises from unknown regions within. He saw the dream as significantly analogous to a hysterical symptom.
On the surface, they both appear meaningless and bizarre, but they become understandable when understood as veiled expressions of an unconscious clash between competing motives.
Freud developed an elaborate theory and how the mind works while asleep. In 1953 sleep researchers led by Nathaniel Kleitman made the important discovery of rapid eye movement--or REM-- sleep. Curious about the long-standing observation that the eyeballs of sleeping subjects in both humans and animals periodically move during sleep, they connected laboratory subjects to equipment that measured their brain waves, muscle tone, and eye movement. About 90% of the time when subjects were awakened during REM sleep, they reported a dream.
Prior to laboratory REM research, it was unknown how frequently Humans dreamed. Some theories even held that dreaming was a signal of mental disturbance. With laboratory REM research, however, subjects can be awakened after each REM period in order...