Quoting Jays*Mama:" People keep telling me to let my baby sleep too, but she will just keep sleeping. My baby was born the ... [snip!] ... told me to wake her every 3 hrs for atleast a couple weeks to make sure she gains her birth weight back. Listen to the doctors."
my pedi said when they're very small and early, they'll "forget to wake up" to eat.
so, you gotta wake her up.
we always start off with a diaper change, this usually gets their eyes open.
if not, i take 'em to the front door and we stand in the door way for a min. the combination of air, sun and wind usually wakes them right up.
if that fails, a wet rag, blowing on her face, any combination of those.