Hormonal Secretion of Nurses Engaged in Fast-rotating Shift Systems.

The aim of the study was to assess whether fast-rotating shift systems, including one or two consecutive night shifts, would cause significant disturbances of the normal hormonal patterns of ten young female nurses working in an intensive care unit. Plasma cortisol, serum prolactin, and growth hormone were measured at the start, middle, and end of one morning (07-14), one afternoon (14-21), and two night shifts (21-07); urinary excretion rates of 6-sulfatoxymelatonin (aMT6s), adrenaline (epinephrine) and noradrenaline (norephinephrine) were determined for each half of the four shifts. During the night shifts, the hormones more sensitive to exogenous components, such as catecholamines, prolactin, and growth hormone, showed an immediate response to the shifted sleep/activity cycle, evidencing a "masking effect" due to the work activity. On the other hand, hormones having stronger endogenous components, such as cortisol and melatonin, showed a more stable pattern, with a slight tendency for partial adjustment of cortisol during the second night.