Those two symptoms dont diretcly mean that you are going to project. I have learned there is a number different physical circumstances that can produce those effects, including narcolepsy and vastibular problems.
I only concider those projection symptoms when they lead to an actual psychic disassociation. You'll know this when you have actually "lifted" from your laying position, or something else along those lines. In my case, I usually fall to the floor, either by sliding away, or passing through the bed. And then of course, I know it is real, when I can stand up, then go about my business.
When that happens to you, do you ignore it, or do you try to make it stronger? Doing either can cause you to project, as long as you are in a passive state (physically and mentally). Getting too excited, or thinking too much, can cause the process to reverse itself; which is why I dont advocate any method that only validates one's physical circumstance.