"That shouldn't be. Mountain Dew has nearly 20% more caffeine in it than Coke."

Hmmm...interesting. Maybe it's the combination of sugar, syrup, caffeine, etc. I guess everybody's body chemistry is different.

I can't drink coke after 6 PM or I'll be up all night, but I can drink MD any time.

Then again, since I was a teen, I get monster headaches if I'm not spiked up on coke/coffee within an hour of waking. So my insides have been FUBAR for years.