LOL! I teach ESL to Korean students who study through almost all of their waking hours. Often when I ask students, "What is your hobby?" they say "Sleeping." Also, when I ask them, "What do you want to do?" many say, "I want to sleep." I told them sleeping isn't a hobby, but for many of them, the only free time they have in when they sleep (which is only 5-6 hours a day.) I used to think that students were falling asleep in class because my class was boring, but my co-teacher assured me that this happens all the time.
Back to the topic though, I can completely relate to feeling tired, zoned out and burnt out most of the time. Part of that is probably due to trying (in vain) to manage 20 classes of about 30 middle school students a week (of course, my co-teachers help me a lot. I'm usually so focussed on teaching the lesson that I don't see much of what the students are up to. Probably related to AS) It's also partly due to living in a terribly crowded country surrounded by people with no concept of personal space and privacy. Another factor is, as was mentioned, processing things differently than NTs. On top of that, I'm carrying around extra body weight and feel too self-conscious in this appearance-obsessed no-privacy culture to go the gym and be gawked at. So it could be the onset of diabetes, as I seem to have picked up a lot of the symptoms lately such as excessive thirst. Having zero energy and brain fog are also listed as warning signs of diabetes. You might want to look into that as well.