:Objective:Sleep difficulties are associated with cognitive and behavioral problems in childhood. However, it is still unclear whether early sleep difficulties are related to later development. We studied whether parent-reported sleep duration, night awakenings, and parent-reported sleep problems in early childhood are associated with symptoms of inattention and hyperactivity at the age of 5 years.Method:Our study is based on the Child-Sleep birth cohort initially comprising 1673 families, of which 713 were retained at the age of 5 years. We used the Brief Infant Sleep Questionnaire and the Infant Sleep Questionnaire, which were filled out by the parents when their child was 3, 8, and 24 months and 5 years old. Symptoms of inattention and hyperactivity at the age of 5 years were assessed using the Strengths and Difficulties Questionnaire and the Five-to-Fifteen questionnaire.Results:Sleep duration at the age of 3, 8, and 24 months was associated with inattentiveness at 5 years of age. Moreover, parent-reported sleep problems at the age of 24 months were related to both inattentive and hyperactive symptoms at the age of 5 years. Finally, at the age of 5 years, parent-reported sleep problems and night awakenings were associated with concurrent symptoms of inattention and hyperactivity.Conclusion:Our findings suggest that certain sleep characteristics related to sleep quality and quantity in early childhood are associated with inattentiveness and hyperactivity at the age of 5 years. Interestingly, sleep duration in early childhood is consistently related to inattention at the age of 5 years.

Sleep problems and too little sleep are prevalent in young child psychiatric patients, and they relate strongly to the intensity of psychiatric symptoms. Identification and treatment of sleep problems should be a routine part of the treatment plan for young child psychiatric patients. The results emphasise the need for assessing sleep in young child psychiatric patients, as treating the sleep problem may reduce psychiatric symptoms.