Learning and studying a language is SURPRISINGLY tiring. I used to experience this a lot when I was in Budapest, because so many linguists go there to learn the weirdo language. I did a week-long immersion course to become proficient in Hungarian, and I have never been more exhausted in my life. My classmates and I were amazed at how draining it is...
I think I'm becoming tired so easily in the uni because I'm bored with it. It's nowhere near engaging or curiosity-entertaining that I was hoping for it to be. No wonder people start reading on their tablets soon after a lecture starts. I'm going to have to make my own effort to find stuff to learn simply not to become dumber out of boredom.
So true. The first few weeks of studying abroad in Canada were much more mental effort than I'd imagined...going from talking Dutch all summer to not hearing Dutch more than once a week is quite a difference. After about three weeks, my brain decided "okay we're now gonna switch over to English" and that mental drain dissipated. (Switching back to Dutch was a similar process - extra weid because it legitimately feels like you're relearning your mother tongue. My Dutch used English syntax for like, a month.)