sleep together

band together

to unite, to come together

bang some heads together

Attempt to get results from a previously ineffectual or argumentative group, typically by coercion or force.

beauty sleep

Originally, sleep taken before midnight, on the belief that early sleep hours conduce to beauty and health; now (chiefly humorous), sleep at any time needed by one to stay beautiful; (countable) an instance of such sleep.

big sleep

Death.

birds of a feather flock together

People of similar character, background or taste tend to congregate or associate with one another; it is easier to establish friendships with people that one has a lot in common with.

bring together

To cause people to do something together; to bring about togetherness.

cry oneself to sleep

To cry until or to fall asleep.

eat, breathe, and sleep

To devote one's time obsessively to.