Objectives: Sleep disturbances are often associated with emotional/behavioral problems in young children, but whether the association differs among Asian countries remains unknown. This study aimed to investigate the association between sleep disturbances and emotional/behavioral problems in Chinese and Japanese preschoolers and to explore potential differences.Methods: Participants were 1,020 Chinese preschoolers from 10 cities and 438 Japanese preschoolers from 1 city aged 4 to 5 years. Parents filled out the Children's Sleep Habits Questionnaire (CSHQ) and the Strengths and Difficulties Questionnaire (SDQ).Results: Chinese children with sleep disturbances (defined as total CSHQ score >41) demonstrated more peer problems than children without, while there was no such difference in Japanese preschoolers. Domains of sleep disturbances associated with emotional/behavioral problems in Chinese children were sleep disordered breathing and daytime sleepiness, yet in Japanese children were sleep anxiety and night wakings. Children with a higher score of sleep anxiety showed more emotional problems in Japan, but fewer conduct problems in China.Conclusions: Sleep disturbances were associated with emotional/behavioral problems in preschoolers with differences between China and Japan, indicating subcultural differences in preschoolers' sleep within Asian countries.Abbreviations: CSHQ: Children's Sleep Habits Questionnaire; SDQ: Strengths and Difficulties Questionnaire; ANCOVA: analysis of covariance; SD: standard deviation; CI: confidence interval.