Swapna is the Sanskrit word for the dreamstate. Swapna in Hindu philosophy is a state of consciousness when a person (or being) is dreaming in sleep. In this state, he or she cannot perceive the external universe with the senses. This state may contain the conscious activities of memory or imagination. It is typically compared with the states of wakeful consciousness (jagrat), deep sleep in which no cognition occurs (sushupti), and the fourth state known as turiya. These four states of consciousness are described in the Chandogya Upanishad and recur commonly in the literature of yoga.
- Shiva Sutra of Vasugupta as translated by: Feuerstein, Georg (2013-09-11). The Yoga Tradition: It's History, Literature, Philosophy and Practice (Kindle Locations 9285-9291). Hohm Press. Kindle Edition. "[Even] during the differentiation [of consciousness into the three modes of] waking, dream sleep, and deep sleep, [there is continuous] emergence of enjoyment of the Fourth [i.e., absolute Reality]. (1.7) The waking state (jâgrat) [consists in conditional or finite] knowledge (jnâna). (1.8) Dream sleep (svapna) [consists in] imagination (vikalpa). (1.9) Deep sleep (saushupta) [corresponding to] illusion (mâyâ) [consists in complete] nondifferentiation (aviveka). (1.10)"
- DIPAK BHATTACHARYA, THE DOCTRINE OF FOUR IN THE EARLY UPANIṢADS AND SOME CONNECTED PROBLEMS in Journal of Indian Philosophy, Vol. 6, No. 1 (September 1978), pp. 1-34. Published by: Springer. Stable URL: https://www.jstor.org/stable/23440028,Accessed: 16-12-2015 00:15 UTC "The four states are spoken of in Maitrî VII. 11.7: "He who sees with the eye, and he who moves in dreams, He who is deep asleep and is greater [than the rest]" and "These states are: - 1) waking, 2) dream sleep, 3) deep sleep (susupti), i.e. deep, dreamless sleep in which the soul becomes temporarily one with Brahman and enjoys a corresponding unsurpassable bliss, and 4) the 'fourth' state (caturtha, turya, turïya), usually called turîya, in which that disappearance of the manifold universe and the union with Brahman on which the bliss of deep sleep depends takes place not as before unconsciously, but with continued and perfect consciousness." p. 5
- Saraswati, Sri Swami Sivananda (2013-06-13). Kundalini Yoga (Kindle Location 2724). Kindle Edition."During the states of waking, dreaming and dreamless sleep, the Vijnana Atma which dwells in this body is deluded by Maya."
- Patrick Olivelle, The Early Upanishads Annotated, p. 23. "The cavity of the heart is the seat of the vital powers and the self and plays a central role in the expla- nations of the three states of awareness—waking, dreaming, and dreamless sleep— as well as of death. In sleep, the cognitive powers distributed throughout the body during the waking hours are gathered together in the cavity of the heart. The space of this cavity is homologized with cosmic space (see CU 3.12.7-9), and in the dream state the person travels about this space seeing and enjoying the same type of things that he experienced while awake. During deep and dreamless sleep, the self slips out of that cardiac space and enters the veins going from the heart to the peri- cardium; there it remains oblivious to everything (see BU 2.1; 4.3-4)."