BackgroundDuring COVID‐19 pandemic, children are confined at home, with changes in family routines.AimEvaluate sleep disorders among Brazilian and Portuguese children during social distancing, and its association with parental perception of child's oral hygiene.DesignIn this cross‐sectional study, Portuguese and Brazilian parents/caregivers of 3‐ to 15‐year‐old children, practicing social distancing due to COVID‐19 pandemic, answered an online questionnaire, from April 24‐26, 2020, evaluating sociodemographic characteristics, child's school activities online, child's sleep quality during social distancing. Two questions from the questionnaire, developed based on previous studies, evaluated the parental perception of child's oral hygiene quality and routine changes during social distancing. Parents/caregivers answered five domains of the Portuguese‐language version of the Sleep Disturbances Scale for Children, evaluating sleep‐breathing disorders, disorders of arousal, sleep‐wake transition disorders, disorders of excessive somnolence and sleep hyperhidrosis. Descriptive, Linear‐by‐linear association, Kruskal‐Wallis and post hoc analysis were performed (P ≤ .05).ResultsParticipated in the study 253 parents/caregivers, 50.2% from Brazil. Most parents (72.2%) reported changes in child's routine during social distancing. Sleep breathing disorders (P = .019), sleep‐wake transition disorders (P = .022), and disorders of excessive somnolence (P < .001) were associated with poor oral hygiene during social distancing.ConclusionSleep disorders are associated with poor oral hygiene during social distancing.