For many, coffee is an eye opener, a pleasant break or a way to make a social connection. However, anxiety and irritability sometimes occur in conjunction with drinking coffee. People who are not regular coffee drinkers are more prone to these side effects, according to an August 2010 study report published in "Neuropsychopharmacology." A number of reseach studies have examined this relationship. Coffee contains many chemicals, but caffeine is the one responsible for causing anxiety and irritability.
Caffeine and Irritabilty
Irritability is an unpleasant feeling of being overly sensitive to stimulation and easily annoyed. The caffeine found in coffee can produce a heightened sense of perception by stimulating the brain. This effect makes a person more aware of mild annoyances, thereby increasing irritability. Caffeine withdrawal in someone used to consuming large amounts of coffee or other caffeinated beverages can also cause irritability.
Caffeine and Anxiety
Anxiety is a sense of apprehension and unease. The same chemical process in the brain that causes the benefits of intensified alertness can actually serve as a double-edged sword, increasing anxiety by making you more aware of all the potential negative outcomes in a situation.
The impact of coffee on anxiety and irritability is individualized. The chemicals in coffee trigger a range of emotional responses, depending on a person's coffee drinking habits, body weight, metabolism and baseline mood. People who have had less exposure to caffeine or who regularly experience more than usual anxiety and irritability -- even in the absence of coffee -- tend to have a stronger response to the effects of coffee. There is also a genetic component to an individual's response to coffee intake.