A new update from ride-hailing giant Uber takes aim at drowsy driving.

In a nationwide update announced Monday, the company is mandating six hours rest for every 12 hours of driving time. The company said the change is an effort to combat drowsy driving.

The update, expected to be rolled out nationally over a two-week period, will prompt drivers to take a six-hour break after 12 cumulative hours behind the wheel. Drivers will receive a warning after 10 hours of driving uninhibited by a six-hour break. A second warning will come after the 11th hour, and a third notification will serve as a 30-minute warning.

After 12 hours, the app will automatically go offline, Uber says, and drivers will be unable to pick up fares for six hours. After the mandatory rest period, the app will reactivate.

Drowsy driving is the cause of up to 6,000 fatal crashes annually, according to the National Highway Traffic Safety Administration.

Uber has previously come under fire for some of its drivers’ extended working hours, which were highlighted most prominently in a February, 2016, New York Post article that showed some drivers were working well beyond 12 hours per day to support themselves. Shortly after the piece ran, Uber agreed to limit its working hours in New York City to 12 hours, Politico reported, the standard for taxicab drivers in the city.

The latest update applies that change nationally. The company said the update is not necessarily driven by the regulations that exist, but rather a push to improve safety and raise awareness of drowsy driving.

“We want to keep our riders and drivers safe,” said Sachin Kansal, Uber’s Director of Product Management. “The approach we have taken is irrespective of who’s responsible for managing this. We want to help the drivers manage that in the app so they have all the visibility, so they know how much they can drive and when they need to go offline.”

Kansal said the app will measure driving time using GPS and telematics to detect whether the vehicle is moving. Short waits, such as those at stoplights, will count against workers’ driving time. But longer waits such as those in airport queues, and other idling exceeding five minutes, will not count.

Because the clock is cumulative, a driver can be prompted to take a break even if they haven’t driven driven for 12 hours consecutively. For example, someone who has picked up fares in two, six-hour spurts — without taking six hours of rest in between — would have their app disabled after the second leg.

“This new feature has tremendous potential to protect not only Uber driver-partners, but also their passengers and, ultimately, all road users,” said Jonathan Adkins, executive director of the Governors Highway Safety Association, in a statement provided by Uber.

In some jurisdictions, which have existing driving time limits, the feature will be adjusted to meet local requirements. Virginia regulations, for example, allow 13 hours of driving over a 24-hour period. Lyft already mandates a six-hour break for every 14 hours of driving.

While the effects of the update won’t be pronounced for most — Uber says nearly 60 percent of contractors use the app for less than 10 hours per week — it could result in some initial surprise, and possible confusion, for riders and drivers.

Kansal said Uber is taking steps to ensure drivers reaching the upper limits of their work time will not be paired with passengers taking long trips, and riders won’t be left stranded when their drivers are suddenly logged off.

“If someone is already in a ride, we’re not gonna boot them, we’re gonna let them finish that ride,” Kansal said. “One of the other reasons why we notify the drivers — 2 hours, 1 hour and 30 minutes before the limit — is exactly so they can manage those situations as well.”