Final answer:
Sleep problems in American school-age children are often due to irregular bedtime routines, excessive caffeine intake, and insufficient physical activity, rather than shorter school hours.
Step-by-step explanation:
Why do American school-age children commonly experience sleep problems? There are numerous factors, but significant contributors include irregular bedtime routines, excessive caffeine consumption, and lack of physical activity. An inconsistent sleep schedule can lead to disrupted sleep patterns, making it difficult for children to fall asleep and stay asleep. Furthermore, caffeine is a stimulant that can delay the onset of sleep and reduce sleep quality. Also, engaging in regular physical activity can promote better sleep, whereas a lack of it may contribute to sleep difficulties. However, shorter school hours are not a commonly cited factor for sleep problems among this demographic.