The development of sleep behavior within the first 5 years of life

Abstract Sleep behavior between 1/2 and 5 years in 320 Swiss children of the first Zurich longitudinal study is reported. The average length of night sleep between 1/2 and 5 years was 11 to 12 hours. Day sleep was noted in 96% of the children between 6 and 24 months, and in 20% at age 5. The total length of sleep between 6 and 18 months was 15 hours per 24 hours. It diminished to 12 hours at age 5. There was a large individual variability of day sleep and of night sleep at all ages. Positive correlations were found between the lengths of day sleep at different ages and between the lengths of night sleep at different ages. The length of day sleep and that of night sleep was negatively correlated between 2 and 5 years. Evening wakefulness was observed in 16% and night waking in 40 to 50% of all children. 18% woke up at least once each night. Night wakening between 2 and 5 years was positively correlated. In about half of the children with evening wakefulness and/or night wakening these sleep behaviors were considered as abnormal by the mothers.