REM sleep is revealed by continuous movements of the eyes during sleep.
At times, dreams may occur during other stages of sleep.
Sometimes the god of dreams is said to carry the dreamer.
Ancient Egyptians believed that dreams were like oracles, bringing messages from the gods.
The Indian text Upanishads, written between 900 and 500 BC, emphasize two meanings of dreams.
In that century, other cultures influenced Greeks to develop the belief that souls left the sleeping body.
They thought that the best way to receive divine revelation was through dreaming and thus they would induce (or "incubate") dreams.
Egyptians would go to sanctuaries and sleep on special "dream beds" in hope of receiving advice, comfort, or healing from the gods.
proposed that dreams shows how the mind engages in thought when not required to produce communicable versions of thought.
The earliest recorded dreams were acquired from materials dating back approximately 5000 years, in Mesopotamia, where they were documented on clay tablets.
However, these dreams tend to be much less vivid or memorable.