Can I describe high school as a challenge I overcame?

Choose something more specific. If you say, "high school", you might as well say, "life". They are looking for a) what you consider challenging b) how you worked through the problem c) how well you can relay that in writing d) what makes you special.

You probably shouldnt use high school because they will think, oh well she hated high school so much why would we want her? ya know. so maybe the overcoming suicide and depression thing. If i were doing it, I'd be doing it over my parents divorce, fathers death, and having a baby in high school. Those are also good ideas.

Actually, I think it is a really good idea. A lot of people can relate to that situation, I know I can. You could talk about the pressures of high school and there are a lot of things you could talk about! Great idea!