I stopped for awhile and drank just the normal ("double" is normal) Rockstar. I felt tingly all over mostly extremities. Now I have a fatty liver I am sure caused by energy drinks, I haven't had one in at least three years.
Coffee and tea are no comparison to energy drinks even a four or six shot espresso is mild in comparison. Although I believe espresso has less caffeine than regular coffee even for equal volumes.
What's odd is I never drank any caffeine until I was about 34 since even a sip affected me making my heart race from just a sip.
I've now left the stupid energy drink drinkers club!