The aim of this study was to assess preschool children's sleep habits and sleep problems and to examine their relationship with emotion regulation. The teachers and mothers of 308 preschool children participated in the study. A Child Information Form and Sleep Habits Questionnaire were applied to the mothers. In this way, the children's age and gender information, co-sleeping habits, bedtime resistance, sleep onset delay, sleep duration, sleep anxiety, night wakings, parasomnias, sleep-disordered breathing, and daytime sleepiness were evaluated. The teachers were requested to fill in an Emotion Regulation Questionnaire. The research findings revealed that scores in the lability/negativity subdimension of the emotion regulation scale were statistically higher in boys. Similarly, scores of 5-year-old children were higher in the emotion regulation negativity dimension. According to the research findings, it was determined that sleep problems did not affect the children's emotion regulation skills.