Temporary staff at online retailer Amazon are working seven days a week to meet customer demand in the run up to Christmas.
The workers have to do a ten-and-a-half hour night shift on Saturday after a five-day week, according to the Metro newspaper.
Amazon says its 4,000 seasonal workers were told of the heavy workload when they were offered the jobs.
Online sales have continued to grow while many high street retailers have seen serious cuts in consumer spending.
Monday 8 December was the biggest online shopping day of the year, with year-on-year sales values up 14%.
The Interactive Media In Retail Group (IMRG) said a combination of continuing consumer confidence in online shopping and heavy retailer promotion saw sales of around £320m.