Introduction: We examined the nighttime sleep habits associated with insufficient sleep quantity and poor sleep quality among healthy preschool-aged Taiwanese children. Materials and Methods: The study population of this cross-sectional survey was a stratified random sample of 3 to 6-year-old preschool children from 19 cities and counties in Taiwan. A caregiver-administered questionnaire was used to collect information on preschooler sleep quantity (sleep duration and sleep latency) and sleep quality (sleep disturbances and disruption) and potentially related sleep habits. Results: Of the 1253 children for whom analysable survey data were collected (children's mean age: 5.03 ± 1.27 years), more than half (53.07%) engaged in bedtime television (TV)-viewing, 88.95% required a sleep reminder, 43.85% exhibited bedtime resistance, 93.6% engaged in co-sleeping (bed-sharing or room-sharing), and only 33.72% slept in a well darkened bedroom. Bedtime TV-viewing, co-sleeping, bedroom light exposure, and bedtime resistance were the primary predictors, without a bedtime TV-viewing habit was the strongest predictor analysed; it explained 15.2% and 19.9% of the variance in adequate sleep quantity and improved sleep quality in preschool children. Conclusion: Sleep loss and poor sleep quality in preschool children could be alleviated, at least partly, by curtailing bedtime TV-viewing, limiting light exposure during sleeping, and reducing bed-sharing habit.