Sleep Like a Baby?

Isn't that phrase supposed to mean that babies sleep well and a lot? Maybe it is referring to very young babies? All I know is that is is not referring to my baby Melody. I really hope that sleep habits can be learned over time because her current patterns are not cutting it. Last night she was up wailing at 3AM for no apparent reason. She went back down, thankfully. This morning I put her down for her usual nap and she wailed until she finally fell asleep for a grand total of 15 minutes. This afternoon I spent extra time soothing her and helping her drift off to sleep. It worked. I looked at the clock when I came downstairs and it said 1:20. At 2:30 she was up wailing. I don't get it. The minute she gains the least bit of consciousness she wails. Why? I desperately want to provide whatever it is she needs to feel secure and whole, but what is that? I know that well-rested children are supposed to wake up happy, but Melody never does. She always wakes crying. Most of the time I can tell that she hasn't slept enough, but there's nothing I can do about it. She seems fine during the rest of the day, thankfully. It's so hard not knowing how to help her. Maybe time will help us all.