I once quit caffeine cold for 6 months: 2 weeks of pure hell then it was like I never craved it until life got real and stressful and I fell off the wagon. Today, I drink my espresso with a dot of lowfat milk now and life is currently too real and stressful to consider trying to drop it again. I do suspect some of us likely have undiagnosed low-level mood disorders leaving us highly functional but discontent and caffeine is the spackling compound used to plug the hole in our souls.