The phrase "sleep sheep" refers to counting imaginary sheep to help someone fall asleep. It is a technique used to relax the mind and overcome insomnia or difficulties in sleeping. Full definition
It must be tough to enable that when someone's perceived freedom is another's perceived harm when inevitably folks have suffered wounds from attacking wolves and neglect from sleeping sheep dogs? (nakedpastor.com)
We have a Cloud B sleep sheep that plays soothing nature sounds. (babycenter.com)