Retailers in some sectors are seeing a lot of post-Christmas joy this year

Paymark has released new data on Boxing Day sales - which show it's becoming one of the year's busiest shopping days.

Spokesman Paul Brislen says there's been increased sales across the board - including in some sectors that surprised them.

He says beauty and hairdressers saw a substantial boost - with many having to go back to work later this week.

Brislen says home decorating stores saw the biggest spending increase of more than 50 percent - while jewellery and sporting goods stores also saw substantial increases.