Sleep duration may vary both interindividually and intraindividually over time. We aimed to identify night-sleep duration (NSD) trajectories among preschoolers and to study associated factors. NSD was collected within the French birth-cohort study EDEN at ages 2, 3, and 5-6 years through parental questionnaires, and were used to model NSD trajectories among 1205 children. Familial socioeconomic factors, maternal sociodemographic, health and lifestyle characteristics, as well as child health, lifestyle, and sleep characteristics at birth and/or at age two years were investigated in association with NSD using multinomial logistic regressions. Five distinct NSD trajectories were identified: short (SS, <10 h, 4.9%), medium-low (MLS, <11 h, 47.8%), medium-high (MHS, ≈11.5 h, 37.2%), long (LS, ≥11.5 h, 4.5%) and changing (CS, ie, ≥11.5 h then <11 h, 5.6%) NSD trajectories. Multivariable analyses showed in particular that compared to the MHS trajectory factors associated with increased risk for the SS trajectory were male gender, first child, maternal age and working status, night-waking, parental presence when falling asleep, television-viewing duration, as well as both "Processed and fast foods" and the "Baby food" dietary patterns at age two years. Factors positively associated with the CS trajectory were maternal smoking, feeding at night, and the Processed and fast foods dietary pattern at age two years, whereas child's activity and emotionality scores at age one year were negatively associated. We identified distinct NSD trajectories among preschoolers and associated early life factors. Some of them may reflect less healthy lifestyles, providing cues for early multi-behavioral prevention interventions.