Let me give you one theory which I like the most (I’m not saying it is THE theory. After all, we know so little about these things in general, so it is always better to stay curious and modest than pretending we know it all.)
First let me provide a brief overview about the Focus Point model of our consciousness. Our consciousness is a vast and seamless “entity” (for lack of better terms) which covers a wide spectrum of “areas.” These areas include our waking state, dream, everything in between and beyond (higher state of consciousness). Just like how camera lense works, “focusing” on an area makes that area appear clearer, and other areas become blurry. Once it’s completely in focus, it becomes the focal point of our “self-awareness”. In this model, falling asleep and entering dreams is essentially the result of our focus shifting into the dream area. What we typically see as a slow and gradual process (falling asleep) can in fact happen in an instant if you could manage to shift your focus quickly. Whether or not this has any scientific basis I truly do not know. However, through years of practice I can indeed do this shift “manually” and sometimes extremely quickly – shifting from complete waking state (with small degrees of controllable physical movements still present at the time of shift) to other states in mere seconds. One interesting state is the intermediate state between waking and dreaming. In this state, our self-awareness is no longer confined in our physical body, but it has not yet entered the “dreamland” and assumed a “dream body.” Instead, it exists in pure intangible, shapeless state. Under this condition you can proceed to form a dream deliberately, or re-focus to move to a higher state of consciousness. This state is also extremely “fragile” because with but the slightest focus change you will return to the physical. In fact, it is not uncommon to be able to feel and command both the physical and mental at the same time, and that can produce some truly amazing results! Okay let’s not get carried away, LOL. Anyway, because our physical input and output are not fully “shielded” from us at this fragile state, our “attention” can be rather easily distracted. For example, sudden sounds, abrupt change of ambient lights, physical touches, and so on. When they happen we inevitably “pay attention” to them and as a result we change our Focus Point back to the waking state.
As you can see from the above, the way to move our Focus Point around is by “paying attention”. If we pay a lot of attention to the physical then we remain physical. Likewise if we pay more attention to things beyond physical then we are moving the focus point of our self-awareness toward them much closer. That, is the theory behind SSILD.
During the SSILD cycles, the first one is almost entirely loaded with the physical. You stare at the blackness behind your closed eyelids, that is physical. If your room is not completely dark you may even see the outside light, and that’s even more physical. You listen, and your ears are filled with outside noises – fans humming, wind blowing, and all that weird stuff. You try to feel and all you could feel is your bodily sensations – blanket rubbing against your skin, some itches, and that horrible backache, etc and etc. However, as you do more cycles, you may start to notice that these external sensations begin to fade, and some “internal” ones begin to appear. The more you cycle, the more attention you are paying to the internal sensations, and less attention are being paied to the external/physical ones. And that, moves your focus point closer to other areas in your consciousness. Think of this as a gentle massage of the mind. You are loosening the grips of the physical and warming up your mind for the more fun stuff.
Then you fall asleep. There are now more chances for you to become lucid in dreams because you have brought more focus/self-awareness with you. Or you may wake up into a false awakening. I suspect this is due to the fact that we all wake up multiple times at the end of each sleep cycle, and immediately fall asleep again. Since our focus point has shifted away from the physical so much during the exercise, when we briefly wake up we don’t have the necessary physical input so our mind simply makes it up for such occasions and immediately goes to sleep again.
Sometimes we do just wake up for real. However, our link with the physical world is still very loose due to the exercise, and thus we have much better chance to manually shift our focus at this stage. This is very powerful stuff. Once you can utilize this, you will almost be able to achieve 100% success with the technique.
Additional note: I always encourage doing SSILD in totally relaxed, lazy manner, and allow your mind to drift into a trance. The trance allows you to relax very quickly and divert your attention from the externals. People often run into problems with SSILD because they try so hard to bring out the sensations, and all that does is to glue their attentions to the external ones. Traditional meditation/relaxation techniques do not mix in well either, because focusing on relaxing your body is effectively, well, focusing on the physicals.
I hope this explains it rather than causing more confusion, LOL. Again, I must stress that this Focus Point model is just one way to look at this “consciousness” thing, and by no means I’m pitching it as a “fact”. It will be a lot more useful if you simply treat it as a “tool”. And in that case, it works wonderfully.
Ps. My DV forum user ID is “cosmiciron”. I no longer participate there outside the scope of SSILD related discussions.