A lay disciple once told me how he had "fluked" a deep Jhana while meditating at home. His wife thought he had died and sent for an ambulance. He was rushed to hospital in a wail of loud sirens. In the emergency room, there was no heartbeat registered on the E.C.G., nor brain activity to be seen by the E.E.G. So the doctor on put defibrillators on his chest to reactivate his heart. Even though he was being bounced up and down on the hospital bed through the force of the electric shocks, he didn't feel a thing! When he emerged from the Jhana in the emergency room, perfectly all right, he had no knowledge of how he had got there, nor of ambulances and sirens, nor of body-jerking defibrillators. All that long time that he was in Jhana, he was fully aware, but only of bliss. This is an example of what is meant by the five senses shutting down within the experience of Jhana.
Although that is not the direct experience of Ajahn Brahm; it is a "lay disciple once told me...", Doesn't it sound scary, if it happens to you while you are not in a safe meditation retreat?
Does anyone have ever had that kind of experiences of not waking up from Jhana?