Amazon recently told workers at its in DCH1 warehouse in Chicago they had to take 10-hour overnight shifts at a new warehouse or risk losing their jobs, according to a new report from Motherboard.

The shifts, known as “megacycle” shifts, typically begin around 1AM and end around lunchtime. The DCH1 warehouse used to have a variety of shifts including an eight-hour overnight shift, a five-hour morning shift, or a four-hour morning shift. But DCH1 is shutting down, the company told workers, and for anyone who wants to move to a new Amazon warehouse the 10-hour megacycle shift is their only option.

The shifts are meant to improve efficiency, according to Motherboard, and workers at delivery stations in other cities have already transitioned to the new megacycle shifts, along with half of Amazon’s last-mile delivery network.

DCH1 Amazonians United, a group representing Amazon workers at DCH1, said the new schedule was “unworkable” for many of the warehouse employees. Ten-hour shifts are not uncommon at Amazon warehouses, and many warehouse employees are part-time workers not eligible for benefits.

Warehouse workers have criticized Amazon for how the company has treated them during the coronavirus pandemic. Workers in New York, Chicago, and Detroit staged walk-offs last spring, which pushed the company to do temperature checks and provide masks, offer partial pay in some instances when it sends sick employees home, and implement cleaning protocols to protect its workers from becoming infected. The company has largely dismissed most of the workers’ complaints as “unfounded,” with executives insulting one fired worker who helped organize a strike at its Staten Island facility last year.

Amazon did not immediately reply to a request for comment Thursday.