Effects of modafinil on vestibular function during 24 hour sleep deprivation

The aim of this research was to investigate the effects of modafinil, a new wake-promoting agent, on vestibular function during 24 h sleep deprivation (SD) so as to provide experimental evidence for the rational use of this drug among air crew. Eight young, healthy male volunteers were exposed to two 24 h periods of continuous wakefulness during the crossover experiment. Initially, 200 mg dose of modafinil was given, and one week later, a matching placebo was administered. The SD time started from 08:00 of the first day to 08:00 of the second day. Drugs were given at 0:00 on the second day. Vestibular function was tested at 21:00 on the first day and 1, 3, 5, 7 h after drug administration. The accuracy of saccade tracking and gains in visual-vestibular optokinetic reflex (VVOR) and optokinetic nystagmus (OKN) in the placebo group decreased during 24 h SD, especially at 01:00-05:00 on the second day, while OKN gains in the modafinil group increased significantly. There were no significant differences in the other vestibular functional indices between the modafinil group and placebo group. The 24 h SD can influence vestibular function to a certain degree, but modafinil may improve OKN.