Nicholas Oates started working at an Amazon fulfillment center in Kansas City, Missouri, in August last year, a few months before Amazon’s ‘peak season’ began in late November, when Black Friday and Cyber Monday sales kick off holiday shopping.

That year, 45% of all US online transactions on Thanksgiving Day and 54.9% of all online transactions on Black Friday were made through Amazon. On Cyber Monday, Amazon sold over 64m items , making up a significant portion of the record $6.59bn in total sales for the day. Amazon noted it was their biggest sales day in company history.

This year, Amazon expanded their Black Friday sale to “Black Friday Deals Week”, encompassing Black Friday and Cyber Monday, and offering different sales on a daily basis.

To help meet such demand during this year’s peak season, Oates, 25, said he was already working 60 hours a week.

Oates explained that as the work volume increases, Amazon workers are not allowed to use personal time and vacation time use is discouraged.

Amazon announced earlier this year a plan to hire 100,000 temporary employees for the 2018 holiday season, though that number has decreased from previous years. The reduction has been attributed to automation and an increased reliance on robots in Amazon fulfillment centers.

Oates says the robots on the warehouse floor often wind up knocking items to the ground, slowing down the work assembly and making it more difficult for workers to keep up picking items.

“It’s a depressing work culture because I’ve seen countless people get chewed up and spit out at this job. One of the biggest, depressing realizations is after I survived peak season, I couldn’t recognize my department anymore. So many people were gone.”

Oates is currently homeless, living out of his car in the Amazon fulfillment center parking lot while working full-time. Oates said he’s struggling with depression. “My quality of sleep has been horrible, I’ve only been getting four to five hours of sleep a night tops,” he said.

Shannon Allen, another Amazon employee who has worked at a fulfillment center in Haslet, Texas, since May 2017, said Black Friday and Cyber Monday sales include many more large items and appliances, which make it more difficult for Amazon workers to keep up with the pace demanded by management.

“When people order the larger items, it makes it a little more strenuous on everybody because mass quantities of larger items are not something that we normally deal with every day,” Allen said.

In an email, an Amazon spokesperson said the company’s “number one priority is to ensure a positive and safe working environment”.

“In recent years, thousands of seasonal associates have gone on to join Amazon on a longer-term basis after the holiday season” the statement said.

The National Retail Federation projects overall holiday season sales to increase by 4.1% in 2018. Increasingly, these sales are shifting toward online retail over brick and mortar retail; in 2017, online sales on Black Friday saw an 18% increase from the previous year, while the number of people who shopped in brick and mortar retail stores on Thanksgiving and Black Friday decreased by 4% .

Though Black Friday shopping is trending toward online retail, millions of Americans will still shop in person at brick and mortar retail stores, where workers face substantial increases in work volume and demanding schedules, often without any additional compensation.

“You don’t get to enjoy Thanksgiving because of Black Friday right after,” said Ludmiala Blanco, an employee for 25 years at a CVS in Los Angeles, California.

“People are very demanding, we have huge lines, and we are understaffed for most of the time people rush in.”

She noted only full-time employees receive time and a half extra compensation for working holidays like Thanksgiving Day but isn’t offered at all on Black Friday.

“It’s really stressful. It’s chaos everywhere. Having to keep up with the pace management expects you to work at, dealing with the mess and the customers, my anxiety is through the roof,” said Noemi Castro, a three-year employee at K-Mart in Los Angeles, California, who is working the morning shift on Black Friday this year.

The director of labor education research at Cornell University’s Industrial and Labor Relations School, Kate Bronfenbrenner, explained these trends are persistent throughout the retail industry.

“There is a very human, personal cost,” Bronfenbrenner said. She noted in the 1980s many places did not open on holidays and were closed on Sundays. “We have moved to a world where the biggest shopping days of the year are on holidays.”

The world’s largest retailer, Walmart, has made efforts to compete with Amazon on Cyber Monday while hosting Black Friday sales at their retail stores across the country.

Walmart does not offer holiday pay or additional compensation to workers on days like Black Friday.

Walmart has faced increasing pressure from workers to raise their minimum wage to $15 an hour. In the wake of Senator Bernie Sanders’ Stop Walmart Act introduced last week to push Walmart to raise their wages, Walmart workers are planning protest events outside of the Walmart billionaire heiress Alice Walton’s New York City Penthouse and Walmart.com headquarters in San Bruno, California, on Cyber Monday.

Kristi Branstetter, a Walmart employee for more than seven years at a store outside of Kansas City, Missouri said: “Retail workers are giving up their time, time with their family to serve customers and we are not making money for ourselves, but making money for the executives and the Waltons who are sitting at home.”