I got a concussion at the end of sophomore year (which didn’t affect my sophomore grades at all, because I didn’t go back to classes after the concussion). Beginning of junior year, for almost all of first semester, it turns out I had post-concussive syndrome but I didn’t realize it for months. I was extremely emotionally fragile and felt like I was struggling in school, but my grades didn’t fall because I just pushed myself even harder to maintain a 4.0. Would it be potentially worth mentioning this experience in a college essay, not as an excuse for low grades but to show the effort/growth that went into high grades? I feel that I genuinely learned something from fighting through my concussion and I’m wondering if it’s something that might be worth writing about.
If it’s worth it to you, then sure, particularly if the prompt is specifically about overcoming a challenge. And if you have a number of supplements to write for each school, then sure.
However, regarding the main essay, if there are experiences / things about yourself that are more central to who you are and how you’re going to use your college education, then it may be better for this small portion of your life to be mentioned more briefly or not at all.