The Federal Aviation Administration is instituting new rest rules for U.S. air traffic controllers to address fatigue issues that may be degrading air safety.

Controllers will now be required to take 10 hours off between shifts and 12 hours off before a midnight shift. The mandate will take effect in 90 days, FAA Administrator Michael Whitaker said in a statement Friday.

“In my first few months at the helm of the FAA, I toured air traffic control facilities around the country — and heard concerns about schedules that do not always allow controllers to get enough rest,” he said. “With the safety of our controllers and national airspace always top of mind for FAA, I took this very seriously — and we’re taking action.”

A representative for the National Air Traffic Controllers Association did not immediately respond to a request for comment.

The new mandate comes amid heightened scrutiny of U.S. air safety. On Thursday, the FAA announced it was investigating a near-miss incident at Washington’s Reagan International Airport. A string of near-miss incidents last year led acting Administrator Billy Nolen to convene an emergency summit on U.S. air safety systems.

Whitaker, who took over as FAA chief in October, commissioned a study on fatigue within weeks of taking office. The subsequent 114-page report found, among other things, that sleep loss, especially in the context of night work and rotating shifts, “engender known safety and performance decrements that can lead to errors, incidents, and accidents.”