Because you’ll get a bigger kick from caffeine if you use it sparingly. In other words, save the seconds for when you’re actually having trouble concentrating, or you need to be alert before climbing behind the wheel. That’s according to Dr. Laura Juliano, a psychology professor at American University in Washington, D.C. She says, caffeine is a drug…and we can build up a tolerance to it. So, not only will our third and fourth cups gradually give us less of an energy boost… But our body will get conditioned to expect caffeine at certain times… And if we skip our usual dose, we’ll start feeling tired. So, try cutting way back on caffeine. That way, when you finally grab a cup of coffee, it’ll actually do something.