RESUMO
To determine effects of the direction of the rotational work shifting on the circadian rhythm and adaptation of physiological and psychological components were investigated with nursing students. Two groups of seven volunteers participated as experimental subjects, and eight nursing students participated as a control group. The directions of rotation work shift were as follows : CW(clockwise)-shift system rotation in the direction of day shift(3 lays), evening shift(3days), off duty(1day) and night shift(5days). and CCW(counterclockwise)-shift system rotation in the reverse direction. Urinary free cortisol and 17-hydroxycorticoster oids in the urine were measured by the solid-phase radioimmunoassay and the colorimetry methods, re spectively. Plasma melatonin was measured by radioimmunoassay. The urinary free cotisol rhythm changed to ir-regular on the evening and night shift in the CCW shift system, whereas the rhythm seems to adapt on night shift in the CW shift system. The daily rhythms of urinary 17-OHCS indicate that they are well synchronized to shift work. These results show that the rotation of shift in the CW direction is more acceptable in terms of the adaptation of hormonal rhythms. These results indicate that the CCW rotation of shift work makes it more difficult for the workers to adapt on a physiological level, and has many more negative effects on nurses when compared with the CW rotation. Thus, a clockwise rotating shift systern seems to be more desirable for the optimal health and performance of nurses.