We conducted a cross‐sectional study to examine sleep in mothers of children with epilepsy and its relation to their children's sleep. A total of 133 dyads of mothers and children with epilepsy aged 1.5–6 years were recruited between 2015 and 2018 from a children's hospital in northern Taiwan. Participating families provided demographic and health information, with children wearing an actigraphy monitor for 7 days and mothers completing sleep and depressive mood questionnaires. We found that 76 (57.1%) of the mothers had poor sleep quality, with 65 (48.9%) mothers having a clinically significant depressive symptom score. Mean actigraphic wake after sleep onset in children was 1.42 (standard deviation = 0.51) hours, with 126 (94.7%) of the children having a clinically significant sleep disturbance score. Multivariate regression analyses showed that higher depressive symptom scores in mothers (β = 0.14; p < .01) and higher sleep disturbance scores in children (β = 0.07; p = .04) were associated with poorer maternal sleep quality, even when maternal demographic characteristics and the child's clinical and epilepsy variables were considered. Findings from our study suggest that sleep disturbances are a shared problem for mothers and their children with epilepsy. Sleep in both mothers and their children with epilepsy should be evaluated in pediatric neurologic practices, with maternal depressive symptoms screened concurrently. Future pediatric epilepsy studies are warranted to examine whether a family‐based intervention program would be effective to improve sleep in mother‐child dyads and to promote better health and functioning of the entire family.