A low morning cortisol level could be a key factor in chronic fatigue syndrome, at least in women, a new study finds.
The study which was carried out by the Centers for Disease Control & Prevention(CDC) is published in the Journal of Clinical Endocrinology & Metabolism. It included 185 participants from Georgia, USA, 75 of whom had been diagnosed with chronic fatigue syndrome (CFS).
Participants were asked to provide samples of saliva as soon as they woke up in the morning, and then again after 30 minutes and one hour. taken as soon as they woke up, and again 30 minutes and an hour later. Levels of the stress hormone cortisol were then measured in each saliva sample by William Reeves, MD, and colleagues from the CDC.
The researchers found that women with CFS showed a different profile for morning cortisol concentrations to those who were healthy, with levels generally being lower in the CFS patients. Cortisol levels in male participants showed no significant differences between CFS patients and the healthy controls
Dr. Reeves said: "People with CFS have reduced overall cortisol output within the first hour after they wake up in the morning, which is actually one of the most stressful times for the body."
The researchers add that these findings do not demonstrate that low morning cortisol is the cause of chronic fatigue syndrome in women, since they do not know which comes first, the disease or the low cortisol.
The study backs up a substantial body of previous research linking CFS to a dysfunction in the hormonal systems the body uses to deal with and manage stress. Reduced response of the adrenal glands (which secret coritsol and other stress-related hormones) has been a common finding in those with CFS.
Source: Nater, U. The Journal of Clinical Endocrinology & Metabolism, Dec. 26, 2007; online edition.