There are 2 possible answers here, I am not sure what you mean.
1.If you had a dreamless life how would you live? This means what would you do if you didn't dream at night.
My answer is that it would not worry me.
2. If you didn't have a dream in your life how would you live?
My answer is that If I didn't have a dream/goal to attain, my life would seem unfulfilled.