RESUMO
Objective Through the establishment of the model of mental fatigue which was induced by continuous mental workload,compare the changes in cognitive function before and after simulated flight and investigate the pattern of heart rate variability (HRV) during the period of simulated flight,thus providing the foundation of screening objective indices for monitoring mental fatigue.Methods A total of 30 participants were informed to take part in a simulated flight for 4 hours.They were arranged to complete the Stanford Sleepiness Scale (SSS) and two cognitive tests,including psychomotor vigilance task (PVT) and shifting attention test (SAT) before and after simulated flight severally.HRV was recorded continuously during the period of simulated flight.Results After simulated flight,the scores of SSS significantly increased (P＜0.05) and mean reaction times to PVT and SAT were longer compared with presimulated flight (P＜0.05).Heart rate (HR) and RMSSD considered as the time domain index of HRV showed significant difference during the period of simulated flight (F=9.81,F=4.75,respectively,both P＜0.05).The results indicate that HR declined and RMSSD of HRV increased significantly,while no significant differences were found in other time domain component and the frequency domain component of HRV.Conclusions The mean reaction times of cognitive tests are sensitive indices to monitor mental fatigue.However,when the time domain component and the frequency domain component of HRV are applied into monitoring mental fatigue,there are still some limitations in different conditions.