I've had problems with coffee for quite a few years. When I'm drinking it regularly, I increase my intake gradually: an extra cup in the morning. A cup in the afternoon. One after dinner. A full thermos on my desk all day.
As I drink more, I sleep less at night, I feel less, and worst of all, I get snappy and irritable with friends and family.
So I periodically go cold turkey. I'll typically switch to green tea, which has much lower levels of caffeine. I'll generally get a better outlook, sleep better, and feel better.
Except I love coffee. So then I reintroduce coffee slowly as a treat, then every day, then it gradually creeps into chain-drinking, and I'm back where I started.
I've recently hit on a formula that seems to work, wherein I can drink all the coffee I want before noon, and no coffee at all afterwards. I have noticed that my mood stays stable, I sleep well, but I still get to enjoy my cup.
The problem with rules like this is the edge cases. Like, what if I have a cup of coffee in hand as the clock strikes 12? What should I do with it? I've been giving myself the benefit of the doubt and made the deal that coffee that was poured in a cup before noon can be finished.
A couple of days ago, I made myself a French press at 11:35. I filled up my large Thermos cup, and there was still enough in the pot to fill up another porcelain cup. All poured before noon, all fair to drink as long as I wanted.
I didn't finish the Thermos cup until 4:30PM. I was up from midnight to 3:30am that night. Damn.
So, lesson learned. No coffee after noon, period. Anything still in the cup goes down the drain.