There are numerous health-related problems caused by long school hours, obesity and increased risk of heart disease being among the most widespread ones. Obesity and heart problems are caused, primarily by sitting, for most of the day, rather than standing or moving around. This side effect can be mitigated, however, by more exercise at school, for example at physical education classes.
Poor posture is a condition many people working too long develop. Particularly vulnerable are children, as their skeletons and muscles are still growing and are not yet stiff enough to resist pressure from the hours of sitting in the same position. To prevent poor posture, teachers need to remind students to keep their bodies in the proper position, their backs leaning against the backs of the chairs.
As children have a long school day, they have little time for friends. This may result in the underdevelopment of social skills and low emotional intelligence. As a result, students can feel lonely and may even develop depression.
As children spend most of their time in the classroom, they may have little time for anything else, including extra curriculum activities, such as music, drama, singing or playing sports. No free time to spare also means students cannot deepen their knowledge in subjects they enjoy. For example, a student with a keen interest in computers would not have much time for his hobby, when he has to devote most time studying subjects he may not like. Accordingly, a system which decides how students spend their time may not be able to produce a true genius, only mediocre generalists.