Objective assessment of exhausted conditions by using the parameters of pupil size and its variability

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The relationships of parameters in pupil size and its variability with exhaustionwas examined. Changes of pupil size and its variation in darkness were recorded continuously for 660-720 seconds using infrared video cameras (IRIS C7364, Hamamatsu, and F2D, AMTech). Average pupillary diameter (PD), slow pupillary oscillations<1.0Hz (FFT amplitude), the pupillary fatigue ratio (PFR, average pupillary diameter/papillary diameter standard deviation), the pupillary unrest index (PUI, cumulative changes in pupil size based on mean values of consecutive data sequences) were calculated as parameters of pupillary activity. Fatigue, sleepiness, subjective symptoms of the subjects were assessed by Vital Exhaustion Scale, Subjective Tiredness Questionnaire, the Stanford Sleepiness Scale, Visual Analog Scale of Sleepiness, and CES-D. Heart rate variability, salivary Ig-A and cortisol, serum cortisol and DHEA-S were simultaneously assessed. Cross-sectional analysis was conducted in 17 hospital nurses (27.0 yrs) working on 3-shift system including night duty, and 38 male workers (43.4 yrs) visiting a clinic for their health check-ups. 13 healthy male students (.21.7 yrs) were examined in an. experimental conditions with 5-hour sleep restriction for 7 days.Results : In nurses, FFT amplitude correlated with fatigue (p<0.01) and sleepiness (p=0.05), and PFR correlated with sleepiness (p=0.04). PD was correlated with salivary and serum cortisol level (p<0.05). In workers, PUI was inversely correlated with depressive symptoms (p<0.05). PD was smaller, FFT amplitude was larger (p=0.03), and PFR was smaller (p=0.02) in sleep-restricted states in the students. Conclusions : Parameters calculated from pupil size correlated with symptoms of exhaustion