If you haven't finished your Christmas shopping, you probably feel pretty stressed out. And if you're a man in the malls, you're burdened by more than just parcels. Shopping can be dangerous to your health.

In a recent study, a group of males was sent out to purchase items on London's busiest shopping street. Psychologist David Lewis, who conducted the study, made a video of the experience.

"We wired them up, measured things like blood pressure, heart rate," Lewis said. "We looked at stress hormones but we also gave them a very special pair of glasses." The frames contained tiny video cameras. This way, scientists were able to see which parts of the shopping trips made the men feel most stressed.

"Every single man in our study became very stressed in the experiment," Lewis said. "In some cases we saw blood pressure that you might associate with a combat pilot flying into action or a riot police officer facing an angry mob. It was not a pleasant experience. It was a kind of shopping nightmare, a day in hell so far as they were concerned."

The study contained one interesting footnote. When the men involved were shopping for themselves, for things like cars, there was no stress at all. It was only when shopping for family and friends that their blood pressures and heartbeats skyrocketed.