anyone's dc a super light sleeper?

dd is 18 mo old and I literally can not check on her night, for fear of waking her up.  I have woken her up the past 3 nights -- 2 she went right back to sleep and 1 she was then up for 2 hours!  We have a white noise machine in her room and a fan outside her door.  We do have a video monitor in my older dd's room (b/c she's in a bed and is more of a wild card once in her room at night!) that I guess I can move, but even with that...I can't really SEE her to know she's ok.  I hate not checking on her but don't want to wake her up.  any tips?

(and I tiptoe in the room, hide at the top of her crib to peek quickly, then tiptoe back out -- but yet I still wake her)