This study measured the sleep attributes of 30 normal 12-month-old children with a computerized movement detector (Actigraph). Data on the child's temperament was based on the Carey Toddler Temperament Questionnaire, which the mother completed. The main finding was that rhythmic children went to sleep earlier and had longer sleep duration; however, their sleep pattern was not more efficient compared to children with irregular rhythmicity. The results of the present study provide only limited evidence to the association between the regulation of sleep-wake cycles and the temperamental characteristics of the child. Hence it may be concluded that within non-referred low-risk infants, temperament does not discriminate between good and poor sleepers. Alternatively, however, the marginal relationship between sleep and temperament demonstrated in the present study may reflect the limitation of maternal perception as a source for temperament assessment.