EEG and eye movement were continuously monitored during sleep in three hyperactive children with minimal brain dysfunction (MBD) syndrome before and during treatment with dextroamphetamine sulfate. The baseline sleep patterns of these markedly disturbed subjects were quite similar to those of seven age-matched controls. Dextroamphetamine sulfate, administered in dosages up to 20 mg, prolonged sleep latency and delayed the onset of the first REM period. Dextroamphetamine sulfate did not affect total sleep time, the constituent EEG sleep stages, or the amount of eye movement activity. These data suggest that the MBD syndrome need not be associated with disordered sleep mechanisms and that the therapeutic efficacy of dextroamphetamine sulfate is probably unrelated to its effects on sleep pattern. We speculate that the therapeutic effects of dextroamphetamine sulfate in the MBD syndrome are on attention rather than arousal mechanisms and that these effects are not "paradoxical."