Midnight refers to more than half of the night, with a wide range, which can be understood as exactly 0 o'clock, or a considerable time period centered on 0 o'clock. Appeared many times late at night in Tang poetry. Although it is all in the evening, the specific time is 10 to 3 o'clock. Let's just say it's definitely not just dark or almost dawn.

One hour is now two hours, because the ancients rested early, so they all fell asleep in the middle of the night, and then the middle of the night is equivalent to our present night.