There's a reason for this, and it's not so much the coffee as when you drink it. Aside from the general stimulation, caffeine also blocks the uptake of certain sleep hormones. So if you're drinking it first thing every morning, you feel more awake, but the residual hormones stay in your bloodstream until the caffeine wears off. Then you feel tired again until it's cleared out. The solution is to wait until you've had some sunlight, or just have it late morning or with lunch. That way you don't have the hormones hanging around until long after they should be gone.