I've been doing it since I was eight, at least--part of what went into the clinically depressed DX slapped on me back then. I was told then (& had it affirmed ever since, even into the bipolar DX) that its a normal, safe coping technique. Since I'm nearly 67 & it hasn't led to harm yet, I have to think they're probably right.
And your description of its being like that "existence" between awake and asleep is pretty accurate. It's not so much that I feel nothing, just that feeling has no significance. I started using it to deal with stress as well during high school.
I know for sure we're not the only ones, mohave rose. I, too, have enjoyed a rich fantasy life. Not surprisingly I spent much of my life working in the theatre, so it proved useful.
Take care.
Roadie