IMPORTANCE: The well-being and development of children is strongly influenced by parents' physical and psychosocial health. Data from small, clinic-based studies suggest that sleep loss may be common in parents of children with atopic dermatitis (AD), but longitudinal population-based studies are lacking. OBJECTIVES: To compare sleep disturbances over time between mothers of children with and without AD and to determine whether these disturbances are associated with the child's disease severity and the child's sleep disturbances. DESIGN, SETTING, AND PARTICIPANTS: In the ongoing Avon Longitudinal Study of Parents and Children, all pregnant women residing in Avon, United Kingdom, with an expected delivery date between April 1, 1991, and December 31, 1992, were recruited. Analyses for this study, a secondary analysis of this cohort, were performed from September 2017 to September 2018. Mother-child pairs were followed up with a time-varying measure of child AD activity and severity and self-reported maternal sleep measures repeated at multiple time points between child ages 6 months and 11 years. MAIN OUTCOMES AND MEASURES: Time-varying binary measures of maternal sleep duration (<6 vs ≥6 hours per night), difficulty falling asleep, early morning awakening, subjectively insufficient sleep, and daytime exhaustion. RESULTS: The study followed up 13 988 mother-child pairs from birth for a median duration of 11 (interquartile range, 7-11) years. Among the cohort, 11 585 of 13 972 mothers (82.9%) were aged 21 to 34 years and 12 001 of 12 324 (97.4%) were of white race/ethnicity; 7220 of 13 978 children (51.7%) were male. Sleep duration (adjusted odds ratio [AOR], 1.09; 95% CI, 0.90-1.32) and early morning awakenings (AOR, 1.16; 95% CI, 0.93-1.46) were similar between mothers of children with and without AD. In contrast, mothers of children with AD were more likely to report difficulty falling asleep (AOR, 1.36; 95% CI, 1.01-1.83), subjectively insufficient sleep (AOR, 1.43; 95% CI, 1.24-1.66), and daytime exhaustion (AOR, 1.41; 95% CI, 1.12-1.78) independent of the child's comorbid asthma and/or allergic rhinitis. For all measures, worse child AD severity was associated with worse maternal sleep outcomes. The magnitude and significance of the associations were largely unchanged after adjustment for child sleep disturbances. CONCLUSIONS AND RELEVANCE: Mothers of children with AD reported difficulty falling asleep, subjectively insufficient sleep, and daytime exhaustion throughout the first 11 years of childhood. However, child sleep disturbances did not fully explain maternal sleep disturbances, and future research should investigate other mechanisms. In caring for children with AD, clinicians should consider maternal sleep disturbances and caregiver fatigue.