I go with the energetic model myself - you're in good company!
Now about that "dying in your sleep" thing ... the way I see it, if you put too much hope into it and when the time comes you find that you're fully awake, you might have a bit of a rough ride. If instead you figure out a way to greet death independent of your surroundings or what you're doing at the time then you might accomplish your passing much easier.
I've always been fascinated by the Japanese samurai and their training for death. They were admonished to think about their death from the moment they woke up until they fell asleep, a fair bit extreme, granted, but it allowed them to perform their necessary duties to their masters. I would never advocate spending so much time on such matters - you'd end up looking like Wednesday Addams

- but I've taken a page from their book (literally - they had a book for samurais on how to live and die) and have thought about my death many times.
I've done "what if" experiments as a form of mediation, envisioning my death from any of a hundred causes, and have found that, at least for me, it was the "fear factor" that had me dreading death. Once I saw the actual process in my mind's eye I was reassured that it was just a variation of sending my soul/spirit/energy on into the world.
As many have said before, what I still fear is the
prolonged death, especially at the hands of well-meaning medicos. That's why I have also investigated several self-termination options and am always willing to learn more, because as the choices are eliminated one by one I fear that my courage and my resolve will disappear along with them. I don't want to die cringing; I want to go with a smile.