The present study was designed to measure many factors that might affect sleep among younger children (primary grades one through six) in public, Catholic, Protestant, and secular schools in Macao, a Special Administrative Region (SAR) of the People's Republic of China. A comprehensive questionnaire was developed following interviews with 12 students and their parents in Macao. After proportional stratification and random stratified of the 59 primary schools in Macao (six geographical districts), 20 were chosen. A total of 5,358 students were selected randomly out of the approximately 29,300 primary students in Macao, of whom 4,101 (76.5%) actually participated. More than half (53.8%) of the students had a delayed bedtime because of tests or examinations, and 46.9% of the students indicated that heavy school work affected their bedtime. Well over half (62.2%) of the students reported that inadequate sleep affected their school performance. On weekends or holidays, 28.1% of the students postponed their wake-up time to 2 hours, and 40.9% of students postponed bedtime to play Internet games. These and other results from this study highlight the importance for school administration, school nurses, and parents of paying substantial attention to factors that may affect sleep in these children and others around the world.