In many TCM teaching materials, each meridian is said to be “most active” during a specific 2‑hour window. People often use this as a lifestyle hint (sleep timing, meals, etc.) rather than a strict rule.
| Time | Earthly Branch | Meridian | Abbrev. |
|---|---|---|---|
| 03:00–05:00 | Yin | Lung | LU |
| 05:00–07:00 | Mao | Large Intestine | LI |
| 07:00–09:00 | Chen | Stomach | ST |
| 09:00–11:00 | Si | Spleen | SP |
| 11:00–13:00 | Wu | Heart | HT |
| 13:00–15:00 | Wei | Small Intestine | SI |
| 15:00–17:00 | Shen | Bladder | BL |
| 17:00–19:00 | You | Kidney | KI |
| 19:00–21:00 | Xu | Pericardium | PC |
| 21:00–23:00 | Hai | Triple Burner / San Jiao | SJ |
| 23:00–01:00 | Zi | Gallbladder | GB |
| 01:00–03:00 | Chou | Liver | LV |
Western-friendly phrasing: “This is a traditional circadian-style map used for teaching. It’s not a diagnosis tool by itself.”