Sleep problems, based on mothers' reports, were examined in children of bipolar, unipolar, and well mothers. Mothers' reports were obtained twice on two of their children : on the younger children when they were between 2 and 3 1/2 years old and again when they were between 5 and 6 1/2 years old; on the older children when they were between 5 and 8 years old and again when they were between 8 and 11 years old. Children's sleep problems also were examined in relation to family diagnosis (i.e. two affectively ill parents, one affectively ill parent, and well parents. Significantly more sleep problems were reported for children with one or two affectively ill parents than for children of well parents.