Jan. 18, 2008 -- Chronic fatigue syndrome may be linked to the stress
hormone cortisol, at least in women, according to a new study.
The study shows that women with chronic fatigue syndrome had lower cortisol
levels in the morning, compared with healthy women.
The study included 185 Georgia adults, 75 of whom had chronic fatigue
syndrome. Those patients had fatigue lasting at least six months with no known
cause and accompanied by at least four other symptoms, such as muscle pain or
Participants provided saliva samples taken as soon as they woke up, and
again 30 minutes and an hour later. The CDC's William Reeves, MD, and
colleagues measured cortisol levels in the saliva samples.
Chronic fatigue syndrome was associated with lower morning cortisol levels
among women, but not among men. Morning cortisol levels were similar for men
with and without chronic fatigue syndrome.
The study doesn't prove that low morning levels of cortisol cause women's
chronic fatigue syndrome. The researchers don't know which came first -- low
morning cortisol levels or chronic fatigue syndrome -- but their findings may
be a clue for researchers.
The study appears in The Journal of Clinical Endocrinology &