Abstract: Objective To investigate the prevalence of attention deficit hyperactivity disorder(ADHD) and sleep disorder among middle school students in Ningbo city.Methods Stratified random cluster sampling was used to select 2 133 middle school students and their parents in Ningbo city for a self-administered questionnaire survey between May and June 2015 with a self-compiled questionnaire and Short Form,Parental Version of the Chinese Swanson,Nolan,and Pelham-IV(SNAP-IV);Insomnia Severity Index(ISI) was used to evaluate sleep status of the students.Results The proportions of the students with normal,critical,moderately abnormal,and severely abnormal SNAP-IV score for ADHD symptoms were 87.2%(1 861/2 133),9.3%(199/2 133),2.5%(54/2 133),and 0.9%(19/2 133),respectively;the boy students reported higher SNAP-IV score than the girl students(z=5.68,P < 0.01) and the students of low grade reported higher SNAP-IV score than the students of high grade (r_s=-2.02,P < 0.05).The proportions of self-reported insomnia were 20.63%(384/1 861),31.66%(63/199),37.04%(20/54),and 42.11%(8/19)for the students with normal,critical,moderately abnormal,and severely abnormal SNAP-IV score.The degree of ADHD was positively correlated to the severity of insomnia(H=4.36,P=0.00).There were no significant differences in the time of going to bed and getting up and the total sleep time among the students with different SNAP-IV score.The students with critical,moderately abnormal,and severely abnormal SNAP-IV score had higher total and domain ISI score than the students with normal SNAP-IV score.The scores of attention deficit and hyperactivity impulse score and overall ADHD score were positively correlated mildly with total ISI score.Conclusion The students with higher SNAP-IV score for ADHD symptoms had a higher incidence of insomnia and the result suggests that the intervention on insomnia could be adopted as one of measures for ADHD treatment.