The name of the study said it all: "Sleepmore in Seattle: Later School Start times Are Associated with More Sleep and Better Performance in High School Students." In 2016-17, Seattle Public Schools pushed back high-school start times by 55 minutes, from 7:50 a.m. to 8:45 a.m. And just like that, students slept an average of 34 more minutes per night and their grades went up 4.5 percent, researchers found. It was yet another entry in a long bibliography of studies showing the benefits of a later start time for teenagers (including "Rise and Shine" by Jennifer Heissel and Samuel Norris, in this issue). For a change that seems like a no-brainer, however, delaying high school times can be notably tough to pull off. The crux of the matter is that schools are a collection of moving parts, from predawn janitorial and food-service prep to busing and afterschool activities. Family work routines are often organized around school rhythms. Shifting secondary-school start times sends shock waves through those systems. In this article, the author takes a close look at practices in three school districts to find out. They are: (1) Saint Paul Public Schools in Minnesota, a diverse urban district of 38,000 students who speak 125 languages at home; (2) Kanawha County Schools in West Virginia, which serves 26,000 students in the capital city of Charleston and surrounding rural communities covering 913 square miles; and (3) Fort Wayne Community Schools in Indiana, which enrolls 29,000 students. Two of these districts--Kanawha County and Fort Wayne Community Schools--have already pushed back high-school start times. Saint Paul is in the homestretch of a years-long effort to do so.