I've felt "groggy" a day after a heavy smoke session but it's never inhibited my ability to absorb information while I am sober.

Then again I smoke about 2-3 times a day and the effects on me are not as pronounced as they are on you. Also alot of my sides have dissappeared with time such as: munchies, severe couch lock, and red eyes.

I'm not sure if this is because my body has adapted or what.

I would do as norkali suggested. Drink plenty of water, take about 3000mg of vitamin C daily (best if spaced out as 3 seperate doses) also be sure to get plenty of exercise.

I work out daily and it definitely helps me physically as well as mentally (I find I'm able to concentrate easier when I am working out regularly and have my body fat sub 12-11%.)

You may want to look into flax seed oil as well. EFAs (Essential Fatty Acids) have been proven to be beneficial to neurons/brain cells. Look for anything with Omega-3, Omega-6 or Omega-9 (preferably all 3). Flax Seed oil is abundant in Omega3 and 9 I believe. A product called Udo's contains all 3.

Alternatively you could just eat a few egg yolks a day and be ok (not the best but it's ok). 2-3 should be good enough.