It's a habit that's shared by at least 50 percent of Americans: a cup of coffee (or espresso, latte, cappuccino) to start the day. People think nothing of this ordinary routine... except for when they accidentally or purposely skip the caffeine. When this happens, people report symptoms of headache, tiredness, and crankiness by mid-afternoon. Is this a psychological or psychosomatic phenomenon? Or is it really tied to that cup o' joe in the morning?
As it turns out, the headaches and overall shift in mood from skipping the coffee routine are caused by acute caffeine withdrawal. Regular caffeine exposure alters in blood flow and electrical activity in the brain, which combine to make people feel more energized and alert. In the absence of caffeine, the expecting brain dilates the cerebral arteries to increase blood flow to the brain. This biological change is thought to underlie the unforgiving caffeine withdrawal headaches.