wee-hours

listen to the pronunciation of wee-hours
Английский Язык - Английский Язык
The very early morning, just after midnight, when most people are asleep
wee small hours
The very early morning, just after midnight, when most people are asleep

He worked into the wee small hours to get everything perfect for the opening day.

wee small hours
The early hours of the morning after midnight
wee hours
early hours of the morning