I work and then whenever I have any other time I'm with my daughter and then I go to sleep. I think you basically have to abandon the dreams of having any other adult activities in your life. You have to go to sleep whenever your child goes to sleep. That's basically how we're doing it.
I don't dream songs. I'm more apt to write dreams down and then to be able to interpret them into a song. I also tend to get up and write prose in the morning from which will come songs.