The consumer demand behind Black Friday is being fuelled by hype generated by the media and the retail sector, according to a sociologist.

U.S. stores traditionally open their doors early on the so-called Black Friday to lure in crowds of holiday shoppers.

Matthew Hayes, a sociology professor at St. Thomas University in Fredericton, said people often purchase goods on Black Fridays not because they need these items but because they want to keep up with people in their social circles.

"There is a lot of hype obviously. It is multiplied by important players in the retail industry," Hayes said.

"The American economy now, perhaps more than ever, is dependent on mass consumption and the Christmas rush is the time where all of these companies go into the black, which is why it is called Black Friday."

It's estimated that sales on Black Friday will be up 3.8 per cent to $11.4 billion this year, according to a Council of Shopping Centers-Goldman Sachs survey.