not lose (any) sleep over / about sb/sth

/nˌɒt lˈuːz ˌɛni slˈiːp ˌəʊvəɹ ɐbˌaʊt ˌɛsbˈiː slˈaʃ ˌɛstˌiːˈeɪtʃ/

/nˌɑːt lˈuːz ˌɛni slˈiːp ˌoʊvɚɹ ɐbˌaʊt ˌɛsbˈiː slˈæʃ ˌɛstˌiːˈeɪtʃ/

to not lose (any) sleep over / about sb/sth

to not be upset or concerned about someone or something at all