Background: This study aims to study prospectively specific sleep patterns and risk of ADHD after adjusting for potential confounders such as obstructive sleep apnoea (OSA) and methylphenidate use.
Methods: A population-representative sample of 514 Chinese preschool children was recruited when in kindergarten (K3). Parents reported on their socioeconomic status and children’s sleep duration. The cohort was reassessed 3 years later when the children were in Grade 3 (P3). Parents reported on children’s sleep patterns and ADHD symptoms. Information on OSA diagnosis and methylphenidate use was retrieved from health records.
Results: Among the 514 parent–child dyads (mean [SD] age, 5.52 [0.33] years), 411 were reassessed (80.0% retention; 9.35 [0.33] years) at follow-up. There were no significant baseline differences between follow-up and drop-out groups. A gradient relationship was observed between probable ADHD in P3 and sleep duration in K3. The risk of probable ADHD was 15.5 per 100 for children with <8 h of sleep in K3, whereas it was 1.1 per 100 for children with 11–12 h of sleep in K3. The adjusted risk ratio was 14.19 (p = 0.02).
Conclusions: Sleep deprivation in early childhood is associated with higher risk of ADHD in middle childhood.
Bibliographical noteCo-first authors: Winnie Tso, Meanne Chan.
The cohort study was supported by two research grants from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project Nos. 743413 and 746111). The funder has no role in (1) study design; (2) the collection, analysis, and interpretation of data; (3) the writing of the report; and (4) the decision to submit the paper for publication.