Effect of methylphenidate on sleep stages and ultradian rhythms in hyperactive children.

The effect of methylphenidate on sleep pattern was assessed in four hyperactive children. Two nights of sleep were recorded before drug administration, sleep was again recorded on the 1st and 21st nights during drug administration, and also on the 1st and 2nd nights of drug withdrawal. All patients showed behavioral improvement during drug administration; however, no drug effect was seen when standard sleep variables such as sleep stages and sleep time were examined. This analysis was supplemented by an examination of the REM cycle and computer extraction of the delta cycle; both are ultradian (40 to 140 minutes) rhythms. These rhythms were found to be intact in hyperactive patients. Although the REM cycle was not affected by drug administration or withdrawal, a trend toward lengthening of the delta cycle was found on drug withdrawal.