the early hours (of the night/morning)
The very early hours after midnight. I was studying for the exam until the early hours of the morning, and now I can barely keep my eyes open! We all danced until the early hours of the night. I love the early hours, when few are awake and one can be alone with one's thoughts.
the ˈsmall/ˈearly hours
(also the wee (small) ˈhours) the period of time very early in the morning, soon after midnight: He died in the early hours of Saturday morning.We stayed up talking into the small hours.