California State Legislature approves later start times 

On October 12, 2019 Governor Newsom signed into law SB 328

The new law requires  "... the school day for middle schools and high schools, including those operated as charter schools, to begin no earlier than 8:00 a.m. and 8:30 a.m., respectively, by July 1, 2022, or the date on which a school district’s or charter school’s respective collective bargaining agreement that is operative on January 1, 2020, expires, whichever is later, except for rural school districts."

Studies on sleep deprivation in teens found here and here