The shopping excitement and frenzy during Christmas can make many of us angry and irritable.
Psychologist Matthew Bambling at the Australian Catholic University in Brisbane, believes that at heart we're all still cavemen and hence seemingly well-adjusted adults turn into misbehaving children.
According to him, the stress and anxiety of Christmas shopping creates in us the instinctual fight or flight response left over from our days as hunter-gatherers.
"Good research has shown that when we're in environments where there are lots of people around us it increases our stress levels," News.com.au quoted him as saying.
"We behave more like people in the wild lands trying to hunt and gather food, and fight other people for food. The problem with that is it leads to some inappropriate behaviour," he added.
Common complaints include store opening and closing times, long queues, last-minute complaints about sold-out stock and parking difficulties.
"It's a bit like road rage. When we're in a hurry we feel entitled," he said.
"We are wired to look after ourselves and our own before we look after strangers. The question is who are we that we're so important that other people should organise their whole behaviour around us and our needs?"
Bambling suggested that talking your way rationally through a situation to avoid losing your temper. And to remember that Christmas stress is actually bad for you.
"Some research studies have shown that when people are chronically angry they are nearly twice as likely to suffer from cardiovascular disease," Bambling said.
"Understanding and kindness towards others this time of year probably would make everybody's Christmas a little bit better."