ShroCat, nothing much to do with age because even when I was a
teen, if I were to languish in bed beyond 10am, I'd be afflicted
with a severe headache for the rest of the day! 
So, no matter what, I just HAVE to get up once I automatically wake
up, which is usually anytime from 5:30am to 6:30am, depending on
how late I went to bed the night before, and I just HAVE to do
something first, like read / brush my teeth / potter around the
house / sit on the couch for a while before heading back to bed and
sleeping in for another one to two hours then I won't get that
dreaded headache for the entire day.
I've never been able to nua in bed the whole day, even if I wanted
to.
What I can do is live
like a cat - be lazy, and take cat-naps throughout the day.
