Research published in the November/December 2002 issue of Psychosomatic Medicine shows a connection between chronic fatigue and a hormonal stress response system called the HPA axis. HPA stands for “hypothalamus, pituitary, adrenal”. It is a system that helps the body to stay stable while under stress.
The study involved 40 subjects between the ages of 30 and 50, half of whom suffered from chronic fatigue syndrome and half who did not. The HPA axis was tested by an ITT (insulin tolerance test), which consisted of a series of insulin injections.
Blood and saliva samples were tested prior to the subjects being put under psychological stress (a fake job interview and solving a math problem while believing they were videotaped). Testing also occurred before and after physical stress, which consisted of working out on a stationary bicycle.
Both the ITT and the testing done prior to and after the stressful events was designed to test the HPA axis. The researchers found that chronic fatigue patients had lower levels of one of the hormones of the HPA axis, adrenocorticotrophic hormone (ACTH) in comparison to healthy volunteers. The ACTH levels in the chronic fatigue patients were low, even before the stress testing or the ITT was administered.