I dimly recall some reference in one of Bailey's (Alice) books ... read this many years ago, that (we're in theosophical world view here) this is the result of the passing of consciousness out of the body through a chakra that was still pretty dense, or contained 'matter' heavy enough to cause a resistance to passage.
Mokay, what the #$%^ does that mean...???
In that world view, there are several 'levels' of 'bodies', each 'vibrating' at a harmonic above the one 'below' it. Chakras supposedly transmit, from one level to another (both directions, as I understand it) some energies while inhibiting others. Their design default is to have a feature which specifically screens the flow of certain energies. If that component is 'burnt away' through meditation, or destroyed or damaged through mechanical means or chemistry, then currents flow. The preferred natural means of evolution is for the lower system to become more sensitive to the finer energies at the next level.... which flow through at any rate.
It all sounds a bit quiant and corny, maybe, but there are various anecdotal tales that support such a view. Piles of psychics report seeing chakras. (I am not a psychic per se, but it is not uncommon, especially with certain people, certain environmental conditions, and certain relative motion, for me to see 'energy' gushing out of a person's forehead or the top of their head.) There are a number of cases of psychics suddenly acquiring their gift after a physical blow to some part of the body, generally the head or the back of the neck.... I think Cayce was one of these, Hurkos another... They get conked with a baseball, pass out, and then wake up reading other peoples' minds and so on.
At any rate, if this is a problem, try willfully locating your consciousness in the areas of various chakras as you drift off to sleep (or aim for OBE, or what have you). Go for center of the head, or the place between the eyebrows, or the heart for best results. The belly chakras can also be used, apparently with dramatic results, but not necessarily pleasant ones. You can also try doing Robert Bruce's energy work applications on the throat chakra (here, presumably, the one that is giving you resistance for now), and that might clear things up.
I used to have this happen a lot as a kid.... I would be drifting off to sleep, and floating... floating... dreaming I was a balloon ... floating, and then:
and there would be a sound like a 12 gauge going off without the echo. Annoying as hell.
My brother thought it was a riot, though, when I said "I dreamed I was a balloon. Then I popped!" He couldn't stop laughing for hours... so there was some good from it.