TAMOTSU Satoshi 1st Dep.Physiol., Hamamatsu Univ.Sch.Med., Research Associate, 医学部, 助手 (60188448)
MORITA Yukitomo Grad.Sch.Electron.Sci.Technol., Shizuoka Univ., Guest Professor, 1st Dep.Physiol, 医学部, 教授 (80034164)
|Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1996: ¥1,200,000 (Direct Cost: ¥1,200,000)
In this study, characteristics of various parameters of the open eyes and other physiological parameters to the vigilance level in daytime and nighttime were investigated A video screen of simulating car driving was presented to eight healthy adult subjects and following parameters were recorded, i.e.eye openness, blinking frequency, eye movement, EEG (O_Z-O_3), ECG,respiration and subjective sleepiness (visual analogue scale, VAS,which defined as 0 for awaking and 100 for extreme sleepiness, and Kuwansei Gakuin Sleepiness Scale, KSS). Recordings in daytime and nighttime were made during 1 hour from 14 : 00 and 22 : 00, respectively.Mean values of each parameter were obtained for every 5 minute.
The hourly mean VAS value in the daytime was 66(]SY.+-。[)13 and signficantly greater than that in the nighttime, 54(]SY.+-。[)15, (p<0.03). The R-R interval in the ECG was 0.830(]SY.+-。[)0.169sec in the daytime and 0.882(]SY.+-。[)0.177 sec at night, the latter being significantly longer (p<0.05). There were no significant differences in eye openness, blinking frequency, eye movement, and % alpha-power of EEG between the daytime and nighttime. Analysis of individual results showed that the eye openness barely changed up to the VAS 80-90, and in 3 out of 5 cases of, in the range above VAS 50, it was smaller at night than that at similar sleepiness. Comparison of the % alpha-power of EEG among individuals with similar VAS values showed no definite tendency in the relationship between the daytime and nighttime. In spite of less sleepiness at night, the %alpha-power was not necessarily small in comparison with the value in the daytime when sleepiness was stronger. The significantly lower heart rate at night suggested the effects of the parasympathetic nervous system. The above results indicated that nighttime drivers are not in the active state physiologically even though they feel less sleepiness, thus calling for greater caution during nighttime driving.