General Trend of Meridian Changes Within 24 Hours

Humans are living beings, and our Qi and blood are in constant flux. Over the course of a day, the changes in meridians mainly reflect dynamic adjustments in the distribution of qi and blood. However, this does not fully align with the traditional “Zi Wu Liu Zhu” (Midday-Midnight Flow Doctrine). The differences and reinterpretation can be summarized as follows:

I. Modern Re-examination of the “Zi Wu Liu Zhu” Theory

1. Contradictions Between Traditional Time Periods and Measured Data

Traditionally, the Lung meridian is believed to dominate from 3:00–5:00 AM (Yin hour). However, continuous 24-hour pulse measurements have not shown a significant increase in the 4th harmonic (corresponding to the Lung meridian) during this time. Similarly, other time periods (e.g., Spleen at 9–11 AM, Heart at 11 AM–1 PM) also do not exhibit consistent or regular harmonic fluctuations.

2. Microcirculation Regulation Hypothesis

Modern research suggests that “Zi Wu Liu Zhu” may reflect microcirculatory regulation:At specific time periods, capillary opening ratios increase in associated meridians (e.g., greater blood flow in Lung meridian during early morning), but not total energy elevation.This mechanism resembles “phased local channel activation”, improving local metabolic efficiency without altering overall systemic energy.

II. Actual Trends of Meridian Changes in 24 Hours

1. Blood Flow Allocation Is Dominated by Activity State

• Resting State:Low-frequency meridians (e.g., Liver, Kidney) dominate in energy.High-frequency meridians (e.g., Stomach, Small Intestine) have lower blood flow, with energy concentrated in deep visceral organs.

• During Physical Activity or Increased Metabolism:High-frequency meridians (e.g., Lung, Gallbladder) experience a surge in blood flow;Low-frequency meridians are suppressed.For example, during intense exercise, blood flow to muscles and skin may increase by 30%, while Liver and Kidney blood flow decreases.

2. Cyclical Metabolic Demands of Organs

• Digestive System (Stomach, Large Intestine):Blood flow increases after eating, partially matching traditional times like Stomach meridian from 7–9 AM.

• Cerebral Blood Supply (Gallbladder, Bladder):Higher demand during daytime activity;Nighttime is dominated by low-frequency meridians for restorative processes.

3. Thermoregulation Impact

• At night, as skin temperature drops, blood circulation shifts toward low-frequency meridians (Liver, Kidney) to maintain core temperature.

• During the day, as body temperature rises, high-frequency meridians (e.g., Sanjiao, Small Intestine) participate in heat dissipation.

III. Core Mechanisms Behind These Changes

1. Harmonic Resonance Principle

Heartbeats produce pressure waves containing harmonics 1–11, each corresponding to a meridian.Daily energy distribution is governed by the autonomic nervous system, not fixed time slots.

For example, the Liver meridian (1st harmonic) maintains baseline energy throughout the day and is only suppressed under intense metabolic demand.

2. Dynamic Blood Oxygen Balancing

When organs become hypoxic (e.g., during prolonged mental work), the related meridian (e.g., Gallbladder) may resonate with pressure waves to "compete" for more oxygenated blood, resulting in a temporary blood flow peak.

3. Posture and Gravity Effects

• During upright activities, high-frequency meridians (e.g., Stomach meridian of Foot Yangming) must counter gravity to maintain blood supply.

• During lying down, low-frequency meridians are better able to conduct energy to distal regions.

IV. Key Differences from Traditional Theory

Traditional Belief	Modern Research Finding
Fixed time periods dominate meridians	Actual dominance is governed by metabolic demand and activity state
Qi and blood circulate strictly by time	Qi and blood redistribute dynamically through harmonic pressure wave competition
Meridians operate independently	Meridians compete and compensate for blood-oxygen resources

V. Clinical Implications

• Diagnosis Timing:When measuring meridian energy, control variables such as 15-minute rest and fasting to avoid activity-induced interference.

• Therapeutic Timing Optimization:

  • Tonifying the Kidney is best during nighttime low-frequency energy phase (9–11 PM)

  • Regulating the Spleen and Stomach is best during the morning metabolic activation window (7–9 AM)

• Exercise & Wellness Recommendations:

  • Morning: Activate high-frequency meridians (e.g., Large Intestine) to promote elimination

  • Evening: Strengthen low-frequency meridians (e.g., Kidney) to support recovery

Conclusion

The 24-hour changes in meridians are essentially a dynamic redistribution of qi and blood resources governed by a harmonic regulatory system, influenced by factors such as metabolic needs, neural regulation, and environmental temperature—rather than rigidly following traditional time-based models.

Understanding this mechanism helps break free from the mechanical framework of Zi Wu Liu Zhu and enables a more precise and evidence-based approach to time-sensitive health cultivation.