That doesn't change the fact that it's a drug. Everyone knows that caffeine provides a significant mental and physical energy lift. Until the levels drop significantly additional caffeine has little or no effect. This is known as tachyphylaxis and is due to neurotransmitter phenomena.
Most people use caffeine in the morning to wake up.
Light is what really wakes you up. Try not using any caffeine and you'll find that you wake up at about the same rate. The big advantage of this is that you are then able to use caffeine as a drug later in the day. Depending on your schedule drink a caffeine beverage with lunch or in the late afternoon. If you work or work out in the early evening save your caffeine boost for the late afternoon.