jumping in on the sleep rant

I'm new to this and need advice! We have a family bed that we share with our S. She is now 12 months old and has been sleeping very restlessly for about the past 4 months. She is a very pleasant child during the day, but is very disagreeable during the night. I nurse her on demand which only calms her down for about a 1/2 an hour. I'm exhausted and don't know what else to do. She is not ill and she only cries more when dad tries to take over.