My personal
take is that she was aware of Happosai's presence and defending in her
sleep (yeah, I know I'm stretching it!), and that she wouldn't want to
clobber her husband in her sleep.
A tought just ocurred to me, one that would fit the Ranma universe
rather well. A "Sleepy Boxing" martial arts style - something along the
lines of "Drunken Boxing", but using sleep instead of alchool.
Extrapolating a bit from what you said above, it might be the only kind
of martial art where Akane can beat Ranma (she'd be a natural at it :)).