In the state of Maryland if someone is photographed nude while
sleeping and unaware is it illegal?  Or is it only illegal if the
pictures are displayed without permission?

It is illegal to display pictures without the permission of the
persons who are shown.

But it isn't to be photographed nude if you arn't aware of...

Not true.  Pictures can be displayed without permission under many
circumstances.  Just take a look at the daily paper.  Photos taken in
public with no expectation of privacy are fair game.

However, photos used for profit or taken secretly under circumstances
where someone would have an expectation of privacy, that's probably
not legally permitted.  It depends on the specifics.  Nudity adds
further complications.