OBJECTIVE: The present study's objective is to assess whether sleep duration affects Early Childhood Development (ECD). A prospective cohort study was carried out with 278 mother-child dyads in the city of Fortaleza, northeastern Brazil, with data collection every 6 months. METHOD: The data used in this study are from the third (18 months) and fourth (24 months) survey waves. Information on sleep duration was collected using the Brief Infant Sleep Questionnaire (BISQ) and information on ECD using the Caregiver Reported Early Development Instrument (CREDI). Crude and adjusted regression models were run for each CREDI domain as an outcome with 5 % significance. RESULTS: The authors found that after adjusting for maternal age and schooling, family income, and the presence of other children in the house, night sleep duration was associated with better ECD scores (cognitive: coef. 0.14
95 % CI 0.04,0.24
language: coef. 0.10
95 % CI 0.01,0.19
motor: coef. 0.10
95 % CI 0.03,0.18
socio-emotional: coef. 0.16
95 % CI 0.06,0.25
overall: coef. 0.14
95 % CI 0.04,0.24), and the time awake at night associated with worse scores (cognitive: coef. -0.12
95 % CI -0.23,0.02
motor: coef. -0.09
95 % CI -0.17,-0.01
socio-emotional: coef. -0.11
95 % CI -0.21,-0.01
overall: coef. -0.11
95 % CI -0.21,-0.01). CONCLUSIONS: Nocturnal sleep duration affects ECD as expressed in all CREDI scores (cognitive, language, motor, social-emotional, and overall).