I've always had this feeling throughout my life. When I was younger I couldn't figure out why people take things so seriously because it all seemed like a play pretend game to me. Two times I had spontaneous experiences (awakening?) where I got to the point where I could clearly see that this world is just a dream which never was. But both times I was very scared as the experience also involved the feeling that a little more of this and I, as a personality, will diasppear too, both times I literally ran screaming in horror trying to think of things that kept me most attached to this reality (my parents) and it 'helped'.
Funny, now for sometime I've been trying to consciously awake again. Sedona Method has been a big help, these days I can go on for a long time without any thought just pure awareness and there is that old familiar feeling on the background that if I continue in that direction this whole 'world' thing will disappear. I still have some unconscious fear that prevents me from going all the way but I am working on it now.
Best wishes,
Nick