北京时间二十四点是夜里12点,也就是凌晨的0点。古时的几时单位是时辰,一时辰为2小时。子时:23:00~00:59,丑时:1:00~2:59,寅时:3:00~4:59,卯时:5:00~6:59,辰时:7:00~8:59,巳时:9:00~10:59,午时:11:00~12:59,未时:13:00~14:59,申时:15:00~16:59,酉时:17:00~18:59,戌时:19:00~20:59,亥时:21:00~22:59。