Do the mother birds stay with their babies in the nest at night?

I have a nest in my backyard with baby sparrows in it. The nest is in a basket hanging on a wall. I took it inside to take a picture of it and hung it back up. I did research and it said sparrows dont smell human scent on their nests even if they touched the babies. Well I went to the mall and now im back and went to check up on the babies, the mother isnt in the nest. Do they sleep with their babies at night? How long does it take until the babies die of hunger because i may need to take the babies in to feed them and care for them myself. Thanks! I appreciate it! :)