What Is Myalgic Encephalomyelitis?
Understanding It Through the GLA Model

In healthy people, the body automatically adjusts to any demand. When you stand up, walk, think hard, or deal with stress, your system quietly:

• increases blood flow to your brain and muscles,
• boosts energy production in your cells,
• keeps your blood pressure and heart rate stable, and
• prevents your immune system from overreacting.

In ME, this “automatic adjustment” fails. The body cannot safely move into a higher gear when stress or exertion appear. Instead of adjusting, your system becomes overloaded.

This leads to:

• rapid exhaustion from small tasks,
• brain fog and difficulty thinking clearly,
• dizziness or “air hunger,”
• heavy limbs and muscle weakness, and
• post-exertional malaise (PEM) – the delayed crash after activity.

The GLA model looks at how four key systems work together to keep you stable:

• Gut – delivers nutrients and immune signals.
• Liver – handles metabolic load, bile acids, and detox.
• Blood vessels and microcirculation – deliver oxygen and fuel.
• Autonomic nervous system – controls heart rate, blood pressure, and “stress gear shifting.”

In ME, all of these are under strain at the same time. Instead of being a smooth, flexible network, the GLA system becomes rigid and easily overwhelmed. When one part struggles, it pushes the others into trouble too.

A. Micro-circulation problems (blood flow issues)

Small blood vessels do not open and distribute blood properly when the body needs more oxygen. This can reduce blood flow to muscles, brain, and organs.

• Muscles feel weak, heavy, or “poisoned.”
• Brain fog and head pressure appear, especially when upright.
• Dizziness and lightheadedness are common.

B. Liver metabolic strain

The liver has to buffer inflammation, toxins, and metabolic stress. In ME it becomes functionally overloaded. Liver blood tests can be normal, but the deeper metabolic pathways struggle.

• Small activities or meals feel like “too much” for the body.
• Recovery after exertion is slow and incomplete.

C. Autonomic nervous system instability

The autonomic nervous system should keep heart rate, blood pressure, and breathing stable. In ME it can become hypersensitive and unstable.

• Standing can trigger rapid heart rate or sudden weakness.
• Temperature control, digestion, and sleep may all feel fragile.
• People often feel “wired but tired” – exhausted, but unable to fully relax.

D. Immune hypersensitivity

The immune system reacts too strongly to minor triggers (activity, infection, stress).

• Flu-like symptoms and body pain flare after exertion.
• Crashes feel like being “hit by a truck” even after small tasks.

Post-exertional malaise (PEM) is the delayed worsening of symptoms after physical, mental, or emotional effort. It is the central feature of ME.

In the GLA frame, PEM happens when:

• Blood flow cannot rise properly during activity.
• Cells switch into emergency metabolism and build up stress signals.
• The autonomic nervous system becomes unstable and overloaded.
• The liver and other buffers cannot clear the stress quickly enough.

This internal stress surge often shows up 6–72 hours after the activity, not immediately, which is why PEM feels so unpredictable.

Ordinary fatigue means:

• You do something hard.
• You feel tired.
• You rest and fairly quickly feel normal again.

ME looks different:

• You may feel “OK” at the time of activity.
• Hours later, your symptoms suddenly worsen.
• The crash can last days, weeks, or longer.
• Each crash makes the whole GLA system more fragile.

This is why standard advice like “just exercise more” can be harmful in ME. The underlying ability to adapt is damaged, so pushing harder often triggers larger and longer crashes.

ME often begins after a clear trigger. Common examples include:

• a viral or infectious illness,
• intense immune activation,
• major physical or emotional stress, or
• overexertion during recovery from illness.

This trigger disrupts the GLA system and can push the body into new, unstable “feedback loops” involving blood flow, metabolism, immunity, and autonomic control. Once these loops are established, the illness can persist for months or years.

Myalgic encephalomyelitis is a disorder where the body cannot safely increase blood flow, energy production, and autonomic stability under stress, leading to delayed crashes and multi-system symptoms.

Different people express this pattern in different ways. Your subtype is simply the pattern of how your GLA system fails under load — which is what the “Understanding Your Subtype” guide explores.