Teenagers' school days shouldn't begin before 8:30 a.m., says American Academy of Sleep Medicine, linking early start times to car accidents, depression and poor academic performance.

In a position statement published Saturday in the Journal of Clinical Sleep Medicine, the sleep research group asserted that later start times aid peak alertness and performance while supporting better mental health and student safety.

As teenagers enter puberty, their biological programming for sleep shifts later, the statement notes, causing a clash with early start times that results in sleep depravation.

“Early school start times make it difficult for adolescents to get sufficient sleep on school nights, and chronic sleep loss among teens is associated with a host of problems, including poor school performance, increased depressive symptoms, and motor vehicle accidents,” said Nathaniel Watson, M.D., the statement's lead author.

“Starting school at 8:30 a.m. or later gives teens a better opportunity to get the sufficient sleep they need to learn and function at their highest level.”

A 2015 analysis from the Centers for Disease Control found that 83% of schools started earlier than 8:30, with 8:03 being the average start time for public middle and high schools. The longstanding debate over school start times typically pits the parents of tired students against school officials who argue later times complicate after-school sporting events.

The academy recommends teens between 13 and 18 years of age sleep at least eight hours each night, but CDC data show two-thirds of students report sleeping fewer than seven hours on school nights.

The dangers associated with a lack of sleep include obesity, athletic injuries, depression symptoms and risky behaviors, the academy said. It even cited a published study that linked a one-hour delay in start times with a 16.5% drop in the rate of car crashes among student drivers.

The circadian shifts experienced by teens can continue well into adulthood: A recent study analyzing college students found their ideal start times to be 11 a.m. or noon.