Sugar intoxication?

I have always wondered why, as an adult, I been affected radically by too much sugar (other than the obvious - my weight gain, but worse is a form of intoxication). Docs tested me for Diabetes and Hypoglycemia and both were negative. I recently found that sugar and sugar substitutes can increase serotonin in the brain which explains my symptoms. Caffeine helps control and/or reverse however! Another good reason to cut back on sugar! I am glad I haven't been affected by my regular cola sodas which are my favorites!