late at night; small hours of the morning
Refers to the deep, quiet hours of the night, typically after midnight. Often used in literary or descriptive contexts.
夜更けに一人で散歩するのが好きだ。
I like taking a walk alone late at night.
夜更けまで仕事をしていた。
I was working until the small hours of the morning.
A phone call came in late at night.
I studied until late at night.
I like the stillness of the late night.