Infant temperament ratings and parental reports of sleep patterns and sleep durations were obtained on 105 normal infants. Boys with more difficult temperaments and active sleep patterns had brief attention spans compared to the other children (p = 0.005). Among all infants, active sleep pattern was associated with maleness and increased activity ratings when awake (both p less than 0.05). Infants with easy temperaments slept longer than those with difficult temperaments (14.9 +/- 0.2 versus 12.8 +/- 0.5 hours, p less than 0.001). Gender, maternal prenatal smoking, method of feeding, and infant sleep position did not affect attention span ratings or sleep durations.