Sleep, like eating and toileting, is an individual physical requirement that changes with time as the child matures. Although much about a child's sleep is biologically determined, extrinsic factors, usually through the parents, also mold the child's sleep behavior. Normal sleep for a child is restful to the child and not excessively disruptive to others. Sleep problems interfere with the quality of the child's sleep and frustrate or frighten caretakers. Several sleep problems have their origins in normal sleep behavior from an earlier age. Some, the parasomnias, are caused by self-limited biologic diatheses. Many sleep problems have psychosocial triggers. Sleep disorders only rarely are a primary medical problem that is adequately treated with medication (e.g., narcolepsy). Good history-taking, often accompanied by diary-keeping, will usually identify the problem--the first step in effective treatment. Treatment of a sleep disorder in the pediatrician's office can start with educating caretakers about normative sleep for the age of the child and providing information regarding the cause and natural course of the problem. Treatment also may involve behavioral or psychological intervention or both, but medication is generally not indicated. When needed for short-term treatment, mild sedatives such as antihistamines are used most often. More serious sleep or behavioral problems should be acknowledged by the primary care pediatrician, followed by referral to an appropriate specialist. Inquiry into a child's sleep habits at each well-child visit, coupled with appropriate anticipatory guidance, could make an important contribution to the child and family by preventing problems with sleep and identifying sleep problems early in their evolution. Pediatricians and parents can work together to help children develop good sleep habits that fulfill the child's evolving sleep requirements within the context of the family's needs and expectations.