The Arousal System: a blog series on norepinephrine in ME/CFS

Norepinephrine is usually called the brain’s alertness chemical. In ME/CFS it may be doing something more structural — and the evidence is both promising and thin.

This series looks at one of the newest threads in ME/CFS research: a selective deficit of central norepinephrine — the brain’s main arousal transmitter — and what it might explain.

It is not a promise. The core finding comes from a single, small study and has not been replicated. But it connects several things patients report — effort intolerance, unrefreshing sleep, “wired but tired” — to one measurable system, and it makes testable predictions.

The parts:

1. Norepinephrine isn’t a fuel — it’s a regulator
2. Why ME/CFS might be norepinephrine-low but dopamine-normal
3. The loop that could keep ME/CFS going
4. What a “norepinephrine drug” can and can’t do
5. Wired but tired: arousal that won’t switch off
6. A lever without a pill: the vagus and the locus coeruleus
7. Pupils, grip, and a urine ratio: testing the system without a lumbar puncture
8. No, it’s still not lactic acid — but norepinephrine is part of the fuel story
9. The norepinephrine triangle: narcolepsy, POTS, and ME/CFS

A caveat that runs through the whole series: the central finding rests on one unreplicated cohort of 16 patients (Aregawi et al. (2026)). Everything downstream is a hypothesis built on it.

References

Aregawi, Mesfin, Brian Walitt, Peter Sullivan, Gustavo Norato, J. David Benjamin, and David Goldstein. 2026. “Central Noradrenergic Deficiency in Post-Infectious Chronic Fatigue: Neurobehavioral Correlates.” Brain Communications. https://doi.org/10.1093/braincomms/fcag173.