American teenagers are beginning their schooldays too early, according to government health experts. A new analysis of U.S. school districts found only 17.7 percent of public schools started their days at 8:30 a.m. or later, which is the time recommended by the American Academy of Pediatrics.

In their analysis of data in the 2011-12 Schools and Staffing Survey, the U.S. Centers for Disease Control and Prevention (CDC) and Department of Education found that at an estimated 39,700 American public middle, high and combined schools, the average start time was 8:03 a.m. and that fewer than one in five schools began their days at the recommended 8:30 a.m. start time or later.

The analysis found that Hawaii, Mississippi and North Dakota had no schools that started at 8:30 a.m. or later. In contrast, Alaska and North Dakota had 75 percent or more of schools that did so.

“Getting enough sleep is important for students’ health, safety and academic performance,” said Anne Wheaton, the CDC epidemiologist who led the study, according to “Early school start times, however, are preventing many adolescents from getting the sleep they need.”

RTR49DH2 Students walk through a hallway during a class change at the E.E. Smith High School in Fayetteville, North Carolina, Sept. 26, 2014. Photo: Reuters

Teenagers who are deprived of sleep are more likely than teens who are not deprived of sleep to be either depressed or overweight, as well as to drink alcohol, smoke tobacco and use drugs, the researchers reported. And more than two-thirds of U.S. high-school students do not get the recommended eight or more hours of sleep a night, the researchers said.

Critics of pushing back the starting time at schools have argued that teenagers just need to get to bed earlier. However, biological rhythms that shift during puberty make teens sleepier in the later hours of the night, causing them to need to sleep later in the mornings, the CDC’s Wheaton said.

Meanwhile, one of the biggest financial roadblocks to pushing back schools’ starting times centers on bus scheduling, as noted by, which pointed out that Montgomery County in Maryland estimated one such change in scheduling would cost $21 million a year.