Clinical training stress and autonomic nervous function in female medical technology students: analysis of heart rate variability and 1/f fluctuation.

To evaluate the level of stress induced by clinical training, ambulatory electrocardiograms from 12 healthy female medical technology students were recorded and the spectral components of heart rate variability (HRV) were analyzed as an index of autonomic nervous function. The HF power reflecting parasympathetic tone was significantly decreased at awakening, compared with that before clinical training (p<0.01). The LF/HF ratio reflecting sympathetic activity also significantly increased during, compared with before clinical training (p<0.01). The slope of the spectral density also changed before and during the clinical training from -1.20+/-0.04 to -1.09+/-0.03 (p<0.05). The 1/f fluctuation of HRV appeared comfortable, and tension was apparently adequate while undergoing clinical training. None of these HRV indices statistically changed while asleep. Thus, the students perceived the stress as a comfortable level of tension and analyzing spectral components and 1/f fluctuation of HRV might be a useful method for evaluating study stress.