It is said that 300 mg of caffeine a day is okay. Anything over that can be bad for your health. 1 oz of regular drip coffee has 20 mg of caffeine, so a 'small' cup of coffee (16 oz) will put .. 320 mg of caffeine in your system, which is already more than the recommended daily allowance.
One solution is to drink espresso-based coffee with added hot water ("Americano'). 1 shot of espresso only has 70 mg of caffeine. So, if you're ordering a 'tall' (small) cup of Americano at Starbucks (it has 2 shots), then you only getting 140 ml of caffeine. A 'grande' cup (3 shots) will have 210 mg of caffeine. In my experience, espresso-based coffee tastes much better than regular drip coffee.
Another solution is to drink green tea. I buy jasmine green tea for 3 bucks at the local pharmacy (24 packets inside) and most truck stops do not charge for cups and hot water. (The bankrupt Flying J in McCammon Idaho where I spent a few days recently did ask for 50 cents for each cup.) I prefer getting paper one-time cups because 'travel mugs' after a while tend to distort the taste, no matter what material they are made of and how thoroughly you clean up.
I found that when the first drink of the day is tea, I drink less coffee afterwards. But if I start the morning with coffee, than I'll be drinking coffee all day and will eventually get much much more than the recommended 300 mg of caffeine! I once quit coffee cold turkey for 2 weeks and noticed right away I started sleeping better and felt less tired at the end of each day.
How 'bout you guys? Anyone willing to switch to green tea for a couple of weeks and see what changes in your body?