The purpose of our study was to determine if common sleep disturbances in young children, such as night waking and bedtime struggle, tend to persist; if they are related to environmental stress factors and are accompanied by other behavior problems; and if their persistence is related to other factors. Sixty children aged 15 to 48 months (mean age 26.4 months) were studied by interviewing their mothers initially and after 3 years. Children with and without sleep disturbances were compared, with the latter serving as the control group. Twenty-five (42%: night waking, 22%; bedtime struggle, 13%; both night waking and bedtime struggle, 7%) of 60 children had sleep disturbances at the initial interview, and of these 25 children, 21 (84%) had persistence of sleep disturbances after 3 years, persistent sleep disturbances had a significant relationship with increased frequency of stress factors in the environment (P less than 0.01). Other generalized behavior difficulties were present in 30% of sleep-disturbed and 19% of non-sleep-disturbed children (P = NS). Co-sleeping (sleeping with a parent or sibling) was noted more frequently in sleep-disturbed (34%) than in non-sleep-disturbed (16%) children. Twenty percent of the mothers at initial interview and 30% at 3-year follow-up perceived their child's sleep disturbances as stressful to them and to their family life. Early identification of the child with sleep disturbances and timely intervention would help both the child and the family.