Svapna [a Sanskrit word] is the dreaming state in which man enjoys the five objects of senses and all the senses are at rest and the mind alone works. Mind itself is the subject and the object. It creates all dream-pictures. Jiva is called Taijasa in this state. There is Antah-Prajna (internal consciousness). The scripture says, "When he falls asleep, there are no chariots in that state, no horses and roads, but he himself creates chariots, horses and roads."
The dreaming world is separate from the waking one. The man sleeping on a cot in Calcutta, quite healthy at the time of going to bed, wanders in Delhi as a sickly man in the dream world and vice versa. Deep sleep is separate from both the dreaming and the waking world. To the dreamer the dream world and the dream objects are as much real as the objects and experiences of the waking world. A dreaming man is not aware of the unreality of the dream world. He is not aware of the existence of the waking world, apart from the dream. Consciousness changes. This change in consciousness brings about either the waking or the dream experiences. The objects do not change in themselves. There is only change in the mind. The mind itself plays the role of the waking and the dream.
The dreamer feels that the dreams are real so long as they last, however incoherent they may be. He dreams sometimes that his head has been cut off and that he is flying in the air.
The dreamer believes in the reality of the dream as well as the different experiences in the dream. Only when he wakes up from the dream, he knows or realises that what he has experienced was mere dream, illusion and false. Similar is the case with the Jiva in the waking world. The ignorant Jiva imagines that the phenomenal world of sense-pleasure is real. But when he is awakened to the reality of things, when his angle of vision is changed, when the screen of Avidya is removed, he realises that this waking world also is unreal like the dream world.
In dream a poor man becomes a mighty potentate. He enjoys various sorts of pleasures. He marries a Maharani, lives in a magnificent palace and begets several children. He gives his eldest daughter in marriage to the son of a Maha-Raja. He goes to the Continent along with this wife and children. Then he returns and visits various places of pilgrimage. He dies of pneumonia at Benares. Within five minutes, he gets the above experiences. What a great marvel!
As in dream, so in the waking, the objects seen are unsubstantial, though the two conditions differ by the one being internal and subtle, and the other external, gross and long. The wise consider the wakeful as well as the dreaming condition as one, in consequence of the similarity of the objective experience in either case. As are dream and illusion a castle in the air, so say the wise, the Vedanta declares this cosmos to be.
Dreams represent the contraries. A king who has plenty of food, dreams that he is begging for his food in the streets. A chaste, pure aspirant dreams that he is suffering from venereal disease. A chivalrous soldier dreams that he is running from the battlefield for fear of enemy. A weak sickly man dreams that he is dead. He dreams also that his living father is dead and weeps in the night. He also experiences that he is attending the cremation of his father. Sometimes a man who lives in the city dreams that he is facing a tiger and a lion and shrieks loudly at night. He takes his pillow thinking it to be his trunk and proceeds to the Railway Station. After walking a short distance he takes it to be a dream and comes back to his house. Some people dream that they are sitting in the toilet and actually micturate in their beds.
As soon as you wake up, the dream becomes unreal. The waking state does not exist in the dream. Both dream and waking states are not present in deep sleep. Deep sleep is not present in dream and waking states. Therefore all the three states are unreal. They are caused by the three qualities: Sattva, Rajas and Tamas. Brahman or the Absolute is the silent witness of the three states. It transcends the three qualities also. It is pure bliss and pure consciousness. It is Existence Absolute.
Excerpted from Philosophy of Dreams by Sri Swami Sivananda, A Divine Life Society publication; First Edition: 1958.