Exactly, MaryP, that's why coffee is awesome.
I completely burned out my caffeine receptors something like 12 years back. I was working around the clock (software engineering at the time) and about 2:30 or so, I noticed I was *hungry* beyond belief. The vending machines were out, there wasn't any stores open anywhere nearby, and the only thing I had to eat was sitting on my desk ... 1/2 pound of chocolate covered coffee beans. I ate them all, and thought I was going to die. My heart was racing, and I was a total mess. But about 6 hours later, I was exhausted and went right to sleep. Ever since, caffeine has had no effect on me. I can drink 2 pots of coffee one day, even in the evening, and go right to sleep at night. I can drink coffee for weeks, and then stop and not have any of the withdrawal symptoms some people have. I just don't react to it any more.