L-Glutamine has been a lifesaver! I was tired a lot (mainly afternoons) and running 3.5 miles 3 - 5 days a week. I have yet to up my carbs (around 20-30 per day) but taking 2000mg per day has increased my energy 10 fold - I am no longer hitting the wall when running either. I am also sleeping better. I attribute this to the L-Glutamine. I was already taking a multi vitamin, magnesium (for cramps), calcium and potassium. Nothing drastic until I added the L-Glutamine. Click http://www.lef.org/magazine/mag99/sep99-report3.html
for information on L-Glutamine.