The bidirectional relationship between children’s bedtime irregularity & hyperactivity/inattention symptoms: a prospective cohort study

Objectives: Although cross-sectional data indicated positive association between hyperactivity and inattention problems and irregular bedtime, longitudinal studies on this topic are scarce leading to no clear inference regarding their directional relationship. Thus, using a prospective birth cohort, we examined the longitudinal relationship between hyperactivity/inattention problems and bedtime irregularity among children aged 5–11 years. Study design: We made use of a nationally representative British birth cohort (N = 15430). Parents reported their children’s hyperactivity/inattention symptoms and bedtime irregularity when the children were aged 5, 7 and 11 years. Data were analyzed using the cross-lagged autoregressive model. Results: Hyperactivity/inattention symptoms (βs = 0.74, ps < 0.001) and bedtime irregularity (0.35 ≤ βs ≤ 0.45, ps < 0.001) remained stable across the 6-year period. Hyperactivity/inattention symptoms and bedtime irregularity consistently predicted each other over time (0.02 ≤ βs ≤ 0.05, ps <.05). Conclusions: Our findings supported a small, yet statistically significant bidirectional relationship between hyperactivity/inattention symptoms and bedtime irregularity during childhood. Findings are consistent with the possibility that regularising bedtime may be associated with improvements on children’s hyperactivity/inattention behaviour. Targeting both hyperactivity/inattention symptoms and bedtime irregularity might be a better approach to optimise overall functioning. © The Author(s) 2026.