I get you. Studying can be hard if you're aiming for very high grades or the school is giving you a lot of homework or projects. My college life was tiring too. I had many nights with 0 or little 💤, in contrast to my work where I had 1 sleepless night only. (I observed that my face was oilier when I had 0 💤 compared to normal 💤.) Instant ☕ was my pal. In college I was so busy studying that I didn't have time for organizations.
Please up your confidence re your intelligence. Humans are learners. It's OK to take time in digesting a hard topic and to err sometimes. Please think re the future. The path is uphill. You'll improve. You'll be smarter.
