Sleep Deprived

Why in the world is it so hard to get a 3 year old to bed? What are we doing wrong? Where have we screwed up as parents? This has been going on since she was 18 months old. And she has had the same bedtime routine since she was 6 months old. The doctors keep telling us it is a phase, or that we just have to find something that works for us. What phase lasts a year and a half, and nothing works for her? We go through our ups and downs. Sometimes she goes to sleep very easily and then there are nights where there are 2 hours of screaming, crying, bargaining, spanking, reverse psychology, etc. Last night was one of those nights. If she was eager to wake up the next morning I would not mind her staying up until she wore herself out, but she can stay up til midnight without passing out and she gets up cranky and crying when I wake her up to get her ready for daycare the next day. How can a child have so much power over you? I'm an adult. I'm almost thirty, and yet this tiny child can break me. I feel like such a failure. To make matters worse, I realize I have the same problem. As much as I do in a day I should pass out at 9:00 p.m. each night, but I can't. I just can't. Some nights I stay up til midnight. So she is just like her mom, however, I can't not wake up in the morning. I can't wake up ill and crying. What does this mean for her as she ages. Will she continue to have this problem?