Night & the Ox

You may be familiar with the twelve animal signs of the Chinese zodiac and how each year is assigned an animal in a twelve year cycle. Back in the day, the Japanese measured their days and nights by these animal signs too. The "time of the ox" being synonymous with the dead of night still survives in this expression:

草木も眠る丑三つ時 - くさきもねむるうしみつどき - The third hour of the ox when even trees and grasses sleep.

In other words: the wee hours in the dead of night.

Note that the 干支 (eto) kanji for Ox: 丑 is different from that used normally: 牛. All the eto kanji are different in this way. I'm a night owl myself and am writing this right now at 丑三つ時.