D.T.
One reason she's waking up and staying up might be because she truly does not know how. It's really hard, but you should stop nursing her to sleep. Most folks recommend teaching them how to soothe themselves to sleep by 6 months... the older they get, the harder it is to break the old habit and learn new ones. Be careful to not introduce a new habit you'll want to break later (like rocking to sleep, or falling asleep with a bottle/cup). There are many books out there and I learned that none of them have the answer -- babies are too different. Get 5-6 of them and then pick out the tidbits that make sense to use for your family and your baby. How much does she nap during the day? There is a fine line between too much sleep and not enough sleep. If a child sleeps too much for naps (most babies go down to 1 long afternoon nap between 12-15 months) they won't sleep as well at night. If they doesn't get enough sleep during the day, they don't sleep at night because they are overtired and restless and can't settle down well. When my son had issues waking at night and being restless we moved his bedtime from 8:30 to 7:30 and all the 'problems' went away. My daughter hasn't had sleep issues because we just did from day one what we had learned from our son. Everything I've read says night terrors don't really begin until after age 2 but since neither of my children had them I don't really know.