Brain Exhaustion?
 

The last 3 days I have been studying 7 or 8 hours daily, for an exam today. The morning of the exam I woke up to find my brain completely exhausted, I can hardly type this.

I can't even think about anything. Has anyone else experienced something like this?

Yes, after my concussion I took a week off from grad studies then really crammed the next two weeks. That was the beginning of my problems. I started fall semester doing about 8 hours worth of reading then at night class my brain was crashed. I eventually had to go on hiatus and have seen much improvement. If I had noticed earlier in the semester I may have been able to carry one or two classes but this was before I knew what PCS was so I kept going full speed with school, coffee, and social drinking and before long it was too late. My brain collapsed in mid October.

If you can somehow lessen your load significantly and balance school with rest and do all the other thing (nutrition etc) you could be fine, but three days at 8 hours would cause me problems too. I'm hoping someday to be able to (though I have no desire to! Reading and writing all day on a screen is bad for the neck anyhow.)

Crashing after such a cognitive load is to be expected. If you need to prepare for an exam, you need to start studying weeks ahead of time. You need to do anything you can to lower the stress level of your studying. I posted some study tips here : http://neurotalk.psychcentral.com/thread199463.html Check out my 2nd post.

I endured this kind of problem during high school and college.