In the Chinese zodiac’s traditional time system, the Rat represents the period from 11 p.m. to 1 a.m.
This interval is called Zi hour and is the first of twelve traditional double-hours. Zi is also the first earthly branch, so the Rat begins both the animal sequence and the daily cycle in this symbolic timekeeping system.
The association reflects the Rat’s reputation for activity at night. Traditional explanations often describe the Rat as emerging or becoming active around midnight, making it a natural emblem for the first watch of the day.
These double-hours are historical divisions rather than modern clock-time rules. They were used in traditional Chinese calendrical and astrological systems, and the exact boundaries can be described differently depending on the convention being followed.