end of a night shift; off night duty
Refers to the state or time after finishing a night shift, often implying tiredness or the start of free time.
I'm sleepy after the night shift, so I'll go to bed right away.
The morning after a night shift feels quieter than usual.
Compound of 夜勤 (night shift) and 明け (end, after). The exact historical derivation is straightforward; the word is a modern compound.