Marital conflict was examined as a predictor of the quality and quantity of sleep in a sample of healthy 8 to 9 year-olds. Parents and children reported on marital conflict, the quantity and quality of children's sleep were examined through an actigraph worn for 7 consecutive nights, and child sleepiness was derived from child and mother reports. Increased marital conflict was associated with disruptions in the quantity and quality of children's sleep as well as subjective sleepness, even after controlling for child age, ethnic group membership, socioeconomic status, sex, and body mass index. The results support the sensitization hypothesis in that exposure to marital conflict may influence an important facet of children's biological regulation, namely sleep.