Maryland advocates concerned about teen sleep are cheering a tweet this week from Education Secretary Arne Duncan, who again signaled support for the idea of shifting the opening hours of schools.

In his tweet, Duncan linked to a U.S. News & World Report story examining the early hours of the high school day and wrote: “Would love to see more districts consider later starting times, particularly for high school students.”

Montgomery, Anne Arundel, Howard and Fairfax counties are in various stages of considering changing high school hours so teenagers can sleep till later in the mornings. The opening bell of high schools in Montgomery and Howard rings at 7:25 a.m., while Anne Arundel’s high schools start at 7:17 a.m., and Fairfax’s at 7:20 a.m.

The leader of the national advocacy group Start School Later, based in Annapolis, pointed out it was not the first time Duncan had taken the issue to Twitter. In August, Duncan tweeted: “Common sense to improve student achievement that too few have implemented: let teens sleep more, start school later.”

“It’s just in­cred­ibly helpful to have education leaders speak out on this issue,” said Terra Ziporyn Snider, the group’s executive director. “Local districts have historically been unable to resolve it on their own, and even the moral support of an education leader can help turn the tide.”