A reader writes, What’s wrong with me? my head? I’m a 18 year old university student who can’t think anymore…

Recently, a reader asked a question:

What's wrong with me? my head?

I'm currently 18 years old and a university student. Recently I realized that something has been going on in my head that is making me unable to think clearly. This week, the symptoms have been getting worse. I'm an "A" student, however a couple days ago I failed an exam that I should have gotten an "A" on because I just couldn't bring myself to concentrate during my exam. For the past couple of days I've had a slight but constant headache. Just now, I took a piece of gum out of the pack and instead of throwing away the wrapper, I threw away the whole pack of gum without realizing until came back to my room and found my whole pack of gum in the garbage. These small instances of inattentiveness have been happening to me more and more recently, which is odd because I'm usually on top of everything, well organized, and clear minded. I've never taken illegal drugs ever in my life, nor have I not been getting less sleep than usual (6-7 hours). All I know is that I was incredibly stressed the past couple of weeks because I had a lot on my schedule. Could that have anything to do with it? Thanks for your time.
My reply to her question was:

Best Answer - Chosen by Voters

Analytical thinking skills burn up to 50% of human glucose and oxygen. Being an A student in a university is like running a marathon constantly. Just people don't respect the effort because its all internally.

You have to find a place where you can decompress - not because of any other fact than the mind (just like a body) needs to recover raw materials (calcium, seretonen, niacin, etc) to continue working so hard.
Get some rest. Respect your limitations.

"In fact, the brain consumes up to 30% of the body’s glucose in a normal day. I found under stress the mind can devoir a whopping 50% of the glucose. (Not to mention a lion’s share of oxygen). Considering it is about 4% of typical body mass it consumes a very large amount of resources. "