Kris,

Based on baby-book type reading and exchanging notes with others, this seems to be an age when sleeping habits changes.

Through the adoption community I have learned about night-terrors.  There are specific things that go on that indicate that it is a night-terror instead of a nightmare.  I don't know the specifics.  A friends daughter experiences night-terror with her afternoon nap.  With the help of professionals, they have learned that she doesn't remember what is going on and (for her) the best thing they can do is calmly rub her back and speak softly.  Trying to wake her up was the wrong thing to do.

I don't know if the hormonal issues our kids have could be related or not.  I do know that at different times of my life I could tell you where I was in my hormonal cycle based on how well I was (or wasn't!) sleeping.

I would suggest talking to your pediatrician.  He/she should be willing to spend some time talking with you about children's sleep habits/patterns/problems etc.

Good luck!