[The effect of long-term nitrazepam administration on sleep cycles in rats]

Single and chronic administration of a low dose of nitrazepam (1 mg/kg) had no effect on sleep cycles in rats. A single injection of a high dose (10 mg/kg) of nitrazepam resulted in prolongation of the total duration of synchronized sleep with a corresponding shortening of desynchronized (paradoxical) sleep. The number of sleep cycles was reduced. Chronic injections of nitrazepam (for 7-14 days) in a dose of 10 mg/kg evoked a gradual prolongation of the duration of paradoxical sleep and an increase in number of sleep cycles. After discontinuance of a long-term administration of nitrazepam (1 mg/kg or 10 mg/kg) prolongation of desynchronized sleep and an increase in the number of sleep cycles were more pronounced in comparison with the last day of chronic administration of the drug.