Electroencephalographic effects of modafinil, an alpha-1-adrenergic psychostimulant, on the sleep of rhesus monkeys.

An electroencephalographic (EEG) study on the rhesus monkey, primate model of human sleep, showed the significant wakening effect of a new psychostimulant, Modafinil. The first experiment, with single administration of three increasing doses of Modafinil (3, 6, and 12 mg/kg), was to determine the efficient threshold dose; the second experiment, with repeated administration of 22.5 mg/kg during 4 days, was to determine whether continuous wakefulness could be obtained without apparent behavioral disorders. Results of the first experiment showed a wakening effect above 6 mg/kg, but 12 mg/kg induced a sharp wakening effect with a significant decrease in all sleep stages. The second experiment induced important insomnia in all subjects for 4 days and 4 nights. No behavioral disorder was observed. Modafinil has a wakening effect at the dose of 6 mg/kg in rhesus monkeys and induces quasicontinuous wakefulness for 4 total days and nights with daily administration of 22.5 mg/kg, with no behavioral disorders. Modafinil should therefore find interesting applications in sleep disorder treatments.