ICSE Class 10 Answered

Most of our vivid dreams come during a type of sleep called rapid eye movement (REM) sleep. REM sleep occurs 3 to 4 times a night. Our eyes never remember any vivid picture of a dream. Our eyes are just instruments to sense the intensity of different wavelengths in the light that enter our eye and all that we perceive afterwards as images is the task of our brain which tries to understand them. It is the brain which sees the vivid picture of the dream through our eyes. This is an example of optical illusion. The area of the dream is controlled by the cerebrum of the central nervous system. As a result, sometimes we can remember the vivid picture seen in the dream.