I don't know whether or not I have it, but I work midnight to noon, so it is no problem. On days off I sleep late, stay up late. No biggie. I have never worked banker's hours in my life.
Midnight to noon are great hours for me too.
This is one of the first things my sleep specialist asked...
He asked me how I felt during the mid morning hours, no matter how much I might have had.
He said if I was miserable at 9:30 am, even if I was able to sleep 8 hours prior, I probably had it.
Here is something that describes the way it feels the best.
"Attempting to force oneself through 9–5 life with DSPS has been likened to "constantly living with 6 hours of jetlag"."
That came from this article...
http://en.wikipedia.org/wiki/Delayed_sleep_phase_syndrome
After a very long evaluation, complete with the diaries, light therapy (which just gave me a headache) and the rest of it, he said it was indeed delayed sleep phase syndrome.
It sounds like you may have the same thing. :(
Good heavens! I meant no matter how much SLEEP I had!!!