During our waking hours, our five senses are constantly conveying information and images to the brain, but during sleep this is not the case.
मस्तिष्क बिना किसी बाहरी संवेदी सहायता के स्वयं अपने अन्दर प्रतिबिम्बों को उत्पन्‍न करता है ।