Increased free cortisol secretion after awakening in chronically stressed individuals due to work overload

The present study investigated the association between chronic stress and cortisol changes during the first hour after awakening in the morning. According to results of a pilot study, it was hypothesized that chronically stressed subjects would show a more enhanced and prolonged increase of cortisol level after awakening compared to non-stressed subjects. In 100 subjects, chronic stress was assessed twice with a 1-week interval between measures and cortisol was repeatedly measured during the first hour of awakening on 3 consecutive days. Results showed that chronically stressed subjects had a significantly larger increase in cortisol (+15.5 nmol/l) compared to unstressed subjects (+9.1 nmol/l). Further analysis indicated a significant sex difference with larger increases in chronically stressed women (+16.5 nmol/l) compared to stressed men (+11.8 nmol/l). From these data we conclude that a repeated measurement of free cortisol in response to awakening should be considered a possible biological correlate of chronic stress. Possible causes, consequences and clinical relevance of this hypercortisolism in chronically stressed subjects are briefly discussed. © 1998 John Wiley & Sons, Ltd.