Facebook is adding a "sleep" mode to its Messenger Kids service to let parents limit when their kids can use it.
The company says parents can now specify the times kids aren't allowed on -- either as a one-time restriction or something recurring, such as after 9 p.m. every school night.
Facebook launched the messaging app aimed at kids under 13 in December. It comes with a bevy of parental controls and no ads. But some child development experts have called for Facebook to pull it, saying it should not be making apps for kids.
It's just the latest example of a tech company offering some concession to critics who say they should tread carefully -- or not at all, when it comes to hawking their wares to kids.