I have had at least 3 dozen lucid dreams or probably more over the last 5 years.When they began I lacked the ability to control them ,I got too excited and eventually woke up.
But with practice,I learned how to remain calm emotionally in the dream and that was key to maintaining long periods inside the lucid dream.
I have had such high levels of conciousness that I have conducted experiments in these dreams,One thing that has always scared me though is this idea of a dream in a dream.
Its hard for me to explain,But I think there is some truth to that whole thing in inception (about getting lost the deeper you go into your unconcious by having a dream inside a dream and having a dream in that dream..ect
Maybe its just an irrational fear and you can't go into a coma or whatever state??