Objective To investigate the effects of modafinil,a new wake-promoting agent, on vestibular function during 24 h sleep deprivation(SD). Method Eight male healthy young volunteers were exposed to two 24 h periods of continuous wakefulness during the crossover experiment. In one period, 200 mg doses of modafinil were given and in the other, separated by one week, matching placebos were administered. The SD time started from 8:00 of the first day to 8:00 of the second day. Drugs was given at 0:00 of the second day. Vestibular function was tested at 21:00 of the first day and 1 ,3,5,7 h after drug administration. Result The accuracy of saccade tracking and the gains of VVOR(visual-vestibular optokinetic reflex)and OKN(optokinetic nystagmus)in the placebo group decreased during 24 h SD, especially at 1: 00～5:00 of the second day, while OKN gains in the modafinil group was increased significantly. There were no significant differences of other vestibular function between modafinil group and placebo group. Conclusion Twenty four SD can influence vestibular function in certain degree,but optokinetic nystagmus can be improved by modafinil.

This paper reviews the etiology , pathogenesis ,prediction and evaluation and other related aspects of motion sickness in order to contribute to further research on motion sickness and to proride the theorotic basis for prevention .

Objective To detect the dynamic visual acuity ( DVA) before and after vestibular habituation of subjects in order to optimize the DVA assessment criteria .Methods The vestibular function examination system was applied to the detection of static and dynamic visual function in 16 healthy subjects .Results When the speed of left or right swinging was fast enough , DVA before and after vestibular habituation was different .Conclusion Subjects with vestibular habituation can reduce their sensitivity to the vestibular system , the changes in DVA are better than before habituation , and the vestib-ular function adaptability training may have effect on DVA .