From my point of view ...
I find it uncomfortable to wear a bra @ home, same goes for most of
my galpals...
As for underwear, I wear it.. *DUH*
But I read that it is much more healthy to sleep without your
panties cuz it reduces chances of vaginal infections & so
on...
For girls who sleep without their underwear @ home, they can always
lock the bedroom door *DUH* 
