FRIDAY, June 4 (HealthDay News) -- When a person gets angry it is often possible to see them physically tense up, but now researchers have found out what else is going on inside the body.

The new study analyzed the biochemical reactions that occur in a person's body when they are angry, right down to the cellular level. Anger not only boosts the heart rate, makes arteries tense up and increases the production of the hormone testosterone, it actually causes levels of the stress hormone cortisol to fall, the researchers report.

For the study, Neus Herrero, a researcher at the University of Valencia in Spain, and colleagues made 30 men angry through the use of 50 first-person phrases known to provoke the emotion. Herrero's team measured the men's biochemical activity before and after they became upset.

Interestingly, the study authors found that anger tends to stimulate the left hemisphere of the brain, the side associated with positive emotions related to closeness. Increased activity in that part of the brain generally results in a desire for closeness rather than the withdrawal triggered by negative emotions.

"The case of anger is unique because it is experienced as negative but, often, it evokes a motivation of closeness," Herrero said in a news release. "When we get angry, we show a natural tendency to get closer to what made us angry to try to eliminate it."

The study findings were published online May 31 in the journal Hormones and Behavior.

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