没日没夜 Origin — Chinese Character Wiki

méirìméiyè

day and night

没沒 méi verbadverb

not have

To be without something; to lack or not possess.
日 rì nounadverb

daytime

daytime; the period between sunrise and sunset as opposed to night
没沒 méi verbadverb

not have

To be without something; to lack or not possess.
夜 yè noun

night

the period between sunset and sunrise; evening; night; (classifier) used as a counter for nights or evenings