Anecdotal reports have suggested that sleeping problems are a frequent complaint from parents of preterm infants. This prospective epidemiological study examined the incidence and stability of sleeping problems of very preterm (< 32 weeks gestation at birth), preterm (32-36 weeks gestation) and fullterm infants, all admitted to special care baby units (SCBU) after birth, in comparison to healthy term infants over the first 5 years of life. Preterm infants were found to have fewer and shorter night-wakings at 5 months. No differences in sleeping behaviour compared with healthy term children were found at 20 and 56 months of age. Similar significant, and moderate, stability of nightwaking from one age to the next were found for exSCBU-graduates and healthy fullterm infants. Parental interventions such as staying with the child until sleep and taking the infant into bed af night were related to nightwaking problems and increased parental distress. It is concluded that prematurity, and thus neurological immaturity and special care experience are less important than caretaking behaviour in the development of sleeping problems in both preterm and fullterm infants.