昼夜を分かたず
ちゅうやをわかたず by day and night day and night

昼夜を舎かず
ちゅうやをおかず continuing day and night

昼夜兼行
ちゅうやけんこう around-the-clock (working) day and night

昼夜帯
ちゅうやおび type of woman's obi, the black and white fabric suggesting the contrast of day and night