Stress Hormones (HPA Axis) and Chronic Fatigue: What We Know Now

Photo by Yuris Alhumaydy on Unsplash

(Educational information only; not medical advice.)

TL;DR

• Your stress-response system—the HPA axis (hypothalamus-pituitary-adrenal)—helps control cortisol.
• People with chronic fatigue syndrome (ME/CFS) often show a weaker HPA response (lower ACTH/cortisol in some tests).
• Newer reviews support a link between HPA axis changes and long-lasting fatigue, sometimes after infections.
• Sleep, gentle activity, steady meals, and stress reduction can support healthier stress responses.

Learn more about how stress affects the immune system.

Quick refresher: What’s the HPA axis?

Think of it as your body’s stress thermostat. The brain talks to the pituitary, which signals the adrenals to release cortisol. Cortisol helps you respond to stress and then return to balance.

What the older study found (and why it mattered)

In a small study from 2002, adults with chronic fatigue had lower ACTH levels and a blunted response to several stress tests compared with healthy people. This suggested the HPA axis might be under-responding in some patients [1].

What newer research adds

• Consistent pattern: Reviews summarize that many people with ME/CFS show HPA axis dysregulation, often a “hypo-cortisol” pattern (lower daily cortisol or weaker responses). It’s not everyone, but it’s common [2].
• Why it might happen: Models suggest long-term stress/inflammation can reset the HPA “set point,” leading to a muted stress response over time [3]
• Post-viral links: Post-infection fatigue (including some long-COVID cases) also shows HPA changes in some studies, supporting a broader post-viral stress-hormone connection [4]
• Gentle ways to support a healthier stress responseThese won’t fix every case, but they’re low-risk, supportive habits:
  • Sleep routine: Consistent bedtime/wake time to steady cortisol rhythms.
  • Light movement: Walking or stretching most days helps regulate stress hormones.
  • Regular meals: Protein + fiber at each meal to avoid big blood-sugar swings (which stress the HPA axis).
  • Breathing/mindfulness: 5–10 minutes daily can calm the nervous system.
  • Work with clinicians: Especially if you have dizziness on standing, severe sleep issues, or post-viral symptoms.