Stress & Post-Exertional Malaise in Chronic Fatigue Syndrome

What's the Relationship?

Exercise can lead to extreme exhaustion in chronic fatigue syndrome. Hinterhaus Productions/Getty Images

Can stress make post-exertional malaise worse in chronic fatigue syndrome (ME/CFS)? A new study suggests that it may.

Post-exertional malaise (PEM) is a hallmark symptom of this condition. People with ME/CFS don't recover normally from exertion, instead suffering more severe symptoms for days or even weeks afterward.

Researchers, including renowned ME/CFS expert Nancy Klimas, set out to determine the relationship between stress management, cortisol levels, and PEM.

Here's why:

  • Cortisol is an important stress hormone. The cortisol awakening response (an increase of cortisol shortly after awakening) has, in multiple illnesses, served as a fatigue-related marker of endocrine (hormone) dysregulation; therefore, it's hypothesized to be relevant to ME/CFS.
  • The cortisol awakening response is also considered a stress-sensitive measure of the HPA axis, which is the system that handles both psychological and physiological stress.
  • Thus, researchers suggest that better stress management could alter the cortisol awakening response, which could in turn influence PEM.

In this preliminary study of 117 adults with ME/CFS, they measured morning cortisol and also got self-reported measures of stress management skills. Their analysis showed that the participants who reported better stress management had stronger cortisol awakening responses and also less severe PEM.

Researchers conclude that future research should examine these trends and also whether improving stress management would lead to reduced symptoms in people with ME/CFS.

Key Definitions:


Hall DL, et al. Psychoneuroendocrinology. 2014 Jul 6;49C:26-31. Stress management skills, cortisol awakening response, and post-exertional malaise in chronic fatigue syndrome.

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