Application of the Sleep Disturbance Scale for Children (SDSC) in preschool age

BACKGROUND: The Sleep Disturbance Scale for Children (SDSC) was originally validated on a sample of healthy children aged 6-16 years, investigating the occurrence of sleep disorders during the previous 6 months. AIMS: The aim of this new study was to assess the psychometric properties of the SDSC in an Italian population of preschool children. METHODS: The SDSC was distributed to the primary caregivers of children recruited via nurseries. Letters describing the study design and requesting the co-operation of the caregivers (parents) and co-signed by the investigators and by the head teacher were distributed with the questionnaire and collected by the teachers. Reliability analysis for evaluating internal consistency and item-total correlation coefficients, and factor analysis were performed. RESULTS: During a 12-months study period, 601 questionnaires from healthy preschool age children (range 3-6 years) were collected. SDSC in preschool children showed a good level of internal consistency (Cronbach's alpha: 0.83) and six factors were derived from the factor analysis by using the principal component method of extraction and rotated with the varimax method: Parasomnias, Difficulty in initiating and maintaining sleep, Sleep disordered breathing, Disorders of excessive somnolence, Sleep hyperhydrosis and Non-restorative Sleep. CONCLUSIONS: The statistical analysis, the internal consistency and the factor analysis support the use of SDSC as an evaluation tool even at preschool age. A different factorial structure from the original SDSC was found due to a different prevalence of the sleep disturbances in younger children, but with similar cut-off total SDSC score.