fox sleep

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.

cry oneself to sleep

To cry until or to fall asleep.

eat, breathe, and sleep

To devote one's time obsessively to.

eternal sleep

Death

fox in the henhouse

Someone untrustworthy placed in a position of trust in which they will be harmful, damaging or detrimental for their own personal gain.

go to sleep

To be affected by paresthesia; to go numb.

one could do it in one's sleep

Said of something that can be done very easily or effortlessly.