[shinesw]

Well, the ideal state to exit your body is one where you suppress all sensory information... To put it plainly, you "forget" that you have a body, you stop looking through your eyes and hearing through your ears, you lose the sense of space and time, you stop feeling your limbs. All that's left is the mind in its purest, most creative form, free of all physical limitations.

We do this naturally when we go to sleep, and that's why we sometimes feel "odd" effects like you mentioned -- they are typical of light trance states.

The problem is, for most people there are two clear cut states: the purely physical state of conscious wakefulness, where you are your body and nothing more, and the unconscious asleep state where nothing at all happens.

When you remember a dream, or a lucid dream, or an OBE, you have been given access to an "in-between" state where you are not strictly physical, yet not fully unconscious either.

Being too awake will usually cause you to be deeply anchored in the physical, you will have a drive to do things physically, and going towards sleep will be difficult.

Being too tired will have the opposite effect, you'll be much more likely to sink into unconsciousness.

So what you said is indeed right -- you're not likely to have an OBE if you're too tired or not tired enough. That's why most people recommend attempting an OBE at a moment where you're slightly drowsy.