MARY LOUISE KELLY, HOST:
Research shows that early school start times are bad for teenagers' mental and physical health, so bad that California has decreed that high schools cannot start before 8:30 a.m. And Florida passed a similar law this year, whereas in Nashville, most public high schools start at 7:05 in the morning. That is among the earliest start times in the country. Catherine Sweeney of Nashville Public Radio reports a new mayor wants to change things - turns out it's not that easy.
CATHERINE SWEENEY, BYLINE: Most teenagers aren't morning people, but it's not their fault. Dr. Kyla Wahlstrom is a researcher at the University of Minnesota studying how education policy affects learning.
KYLA WAHLSTROM: All teenagers have this shift in their brain that causes them to not feel sleepy until about 10:45 or 11 at night.
SWEENEY: But they still need at least eight hours of sleep.
WAHLSTROM: They don't - really fully awake until about 8 in the morning.
SWEENEY: That's because of melatonin. It's something you can buy at the pharmacy, but it's also a hormone our brains release for free to make us sleepy. Teenagers' brains release it on average three hours later than the brains of adults and young kids. That makes getting up for the 7:05 a.m. first period in Metro Nashville public high schools painful. Nashville's new mayor, Freddie O'Connell, wants to push back that first bell.
FREDDIE O'CONNELL: Prematurely early start times, particularly for adolescents, are problematic from student performance, mental and emotional health.
SWEENEY: But getting it done won't be easy, and it could be expensive.
(SOUNDBITE OF BUS BRAKING)
SWEENEY: One reason high schools in Nashville start so early is busing. Like many districts, Nashville uses the same buses and drivers to pick up first high schoolers, then middle schoolers and finally grade schoolers.
UNIDENTIFIED BUS DRIVER: All right. Here we go. Good morning.
SWEENEY: So the thinking has always been, if some kids have to wait for the bus before sunrise, it should be sophomores, not kindergartners. And Mayor O'Connell admits some parents are concerned about the high school day ending later. It could interfere with sports or after-school jobs.
O'CONNELL: Many families have a student who is able to work, is expected to be in the economy.
SWEENEY: But the consequences of sleep deprivation for teenagers are a big deal. It's linked to depression, increased substance use and lower grades. Researcher Kyla Wahlstrom says figuring out later start times is worth it. She's talked with parents and districts that have done it.
WAHLSTROM: Many parents have anecdotally told me that their child is a different child. They are able to speak with them at breakfast. They are chatty in the car. They don't have moody episodes and fly off the handle. The parents are just saying it's remarkable that this has made such a change in their child's life and their family dynamics.
SWEENEY: All because a teenager gets a little more sleep. For NPR News, I'm Catherine Sweeney in Nashville, Tenn.
KELLY: And this story comes from NPR's partnership with Nashville Public Radio and KFF Health News.
(SOUNDBITE OF JAKE BLOUNT'S "GOODBYE, HONEY, YOU CALL THAT GONE") Transcript provided by NPR, Copyright NPR.
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