Ah. Sleep. What the hell is it?
The first thing to understand is that sleep is not some activity of the mind or body. Sleep doesn't SERVE us as some sort of unconscious ability to rejuvenate our energies, at least thats not its direct purpose (actually I guess it depends on how you want to look at it because it does replenish us, by default). The "stages" of sleep are actually different modes of consciousness, but be sure and understand that the waking state is also a type of sleep. In Saivism, limited experience (withing the domain of duality-Maya-subject/object) can be catagorized by the following states: Waking (Beta), Dream (Alpha/Theta) and deep, dreamless (Delta). They blend into each other but there are periods of transision that hold much importance (doorways to turya). My understanding is that we are forced into these states based on our level of pranic energy, low energy=tiredness=dropping into alpha-theta-delta. Essentially we temporarily run out of the necessary organic energy to sustain waking state awarness.
Instead of asking why we need sleep, have you ever asked why we need to wake up? We are impelled by deep causal (karmic) desires for waking state experiences that continually thrust us back to this level of manifestion to have those experiences, i.e. transmigratory existence, birth and death (which sleep represents on a less permanent scale).
This is why I see the brain as a sort of reflecting device. It reflects the independent activities of our non-temporal/spacial minds (what we witness as the firing of neurons, EEG patterns, physical movement, etc...) as well as reflecting the reports of our senses and body to the mind. Mind is a complex, multi-level vibratory matrix of contracted and specialized consciousness. The brain is the physical organ it creates/evolves when it desires to have sensory experience in the material, collective dimension so many people call reality. This is actually just the waking state, another modification of consciousness directed at primary involvement with the senses where our psycho-physical organisim is most clealy defined (personality/body) and we are steeped in the highest degree of duality (internal subject vs. objective/external world). In the grand scheme its no more real than the dream or dreamless state. They are real though in the fact that they are valid experiences within universal consciousness, I don't subscribe to the "everything is some sort of unreal illusion" magazine.
So during the waking state the mind functions accordingly, classical physics, logic, language etc... to deal with this experience of duality. In the dream state (a whole new universe) the concrete structure of waking experience breaks down and our personalities/ego's are amorphous, subtle sensory experience (imagination) replaces the physical senses, irrationality prevails, and new dimensions of knowledge present themselves. In dreamless sleep, the mind stops its activity and only prana functions (keeping us alive and recharging us by default).
Far more important than these three states though, is the "fourth state", a state that transcends and permeates the other three. This is Turya, the state of the witnessing knower. To quote the Shiva Sutras, "The fouth state of consciousness is the everpresent witnessing consciousness of all the three. Even the three states of waking, dreaming, and profound sleep could not be experienced as three different states without a consciousness, a knower that knows all the three. That fourth state is, then, our real Self. It is the everpresent, immortal atman, the deathless, ceasless consciousness that witnesses all that we feel, think, and do. It is the changeless, permanent I that witnesses all our changing I's." With this said, let me confuse everyone by stating that Saivism further defines three phases of turya, "In the turiya state, there are only three phases, viz. tury-jagrat, turya-svapna and turya-susupti.
"The turya-jagrat is that state in which mind as we know it retires completely. Its function ceases and the Super-mind becomes active. . . In this state the activity of the normal mind stops, and unmana or Super-mind supervenes.
"Tury-svapna is that state in which the Yogi crosses the boundary of limitation (of knowledge) and enters the region of unlimitedness (of knowledge). Hence in the tantras, it is called ananta, i.e. unlimited.
"Tury-susupti is known as sarvartha in the tantras, because in this state every thing appears as a from of divine Shakti."
When this state becomes permanent it is called Turyatita, the state of fullest realization. "In it even the distinction between transcendent and the immanent disappears. To one who has entered this state, everything is Shiva."
[This message has been edited by Pratibha (edited March 30, 2001).]
