Purpose: To investigate the association of sleep duration and quality at 12 months and myopia at 3 years. Design: Cohort study. Methods: The Growing Up in Singapore Towards Healthy Outcomes (GUSTO) birth cohort recruited pregnant women at 2 major public maternity hospitals (n = 1236). We included 376 children of Chinese, Malay, and Indian ethnicity who had completed caregiver questionnaires on the child's sleep at 12 months of age [Brief Infant Sleep Questionnaire (BISQ)] and also completed cycloplegic autorefraction and eye axial length (AL) measurement at 3 years of age. Data on total sleep duration and number of night wakings were collected by BISQ. Univariable and multivariable regression models adjusting for potential confounders (age, sex, ethnicity, parental myopia, maternal education level, outdoor time, near work, and height) were used. Results: Thirteen (3.5%) participants were myopic and mean spherical equivalent (SE) was 0.89 diopters (D) (SD 0.88) at 3 years. Total sleep duration and number of night wakings at 12 months were not associated with SE at 3 years (P > 0.05). The total sleep duration (P = 0.07) and number of night wakings (P = 0.49) were not associated with AL in the multivariate model. Total sleep duration in tertile 2 was not associated with AL (P = 0.11) compared with tertile 1. Only total sleep duration in tertile 3 was associated with longer AL (P = 0.006), but there was no association with SE. Conclusions: Sleep duration and quality at 12 months of age were not associated with refractive error at 3 years.