• Fourteen percent of high schoolers and 8 percent of middle schoolers are late for or miss school each day because of tiredness.
• Thirty percent of high schoolers and 6 percent of middle schoolers fall asleep in school each day.
• Wake County, N.C., middle schools switched to an hour later start time and increased test scores in math and reading.
• Sleep-deprived teens participate in more violent and property crime than other teens.
Sources: National Sleep Foundation, Mary Carskadon, University of Nebraska
Sleep deprivation and early school start times contribute to teenage delinquency, risk-taking, depression, pregnancy, obesity and diabetes, a national sleep expert told Chattanoogans on Thursday.
Mary Carskadon spoke at three events sponsored by the University of Tennessee at Chattanooga about her research on sleep and the teenage brain.
Early school start times, changes in teen sleep patterns and outside social pressure are combining to rob teens of vital sleep, which can cause serious problems, Carskadon said.
"Sleep is just getting squeezed out of their lives," she said.
Research by her and other scientists, studies by the Brookings Institute and national polls by the National Sleep Foundation show a correlation between early school start times and a host of behavioral, educational and developmental troubles.
The biobehavioral scientist spoke at the Oak Street Center in First-Centenary United Methodist Church near UTC on Thursday evening and at two other events earlier in the day.
Preteen children tire easily and fall asleep early, which means kids usually get the rest they need, she said. But beginning in puberty, teens' brains begin to allow them to stay up later, often causing them to miss out on the full nine hours of sleep research shows they need for development.
UTC criminal justice professor Robert Thompson spearheaded getting Carskadon to speak.
Thompson has cited research linking early school start times and delinquency in his push for a look at local juvenile crime problems.
Boyd Patterson, coordinator of the Chattanooga Gangs Task Force, spoke briefly at the introduction of the Thursday evening lecture, saying Carskadon's research could benefit the task force's work.
He told the crowd of 50 listeners a majority of people in gangs joined when they were teens and among gang members, the teens often commit the most crimes.
Understanding teen behavior is crucial to working on gang problems, he said.
"Crime suppression and arrests are part of it," Patterson said. "Efforts like this, prevention and intervention, have to be in place."
Minnie Pruitt and Brea Watson, both UTC students and criminal justice majors, said they saw connections between sleep problems and both academic success and avoiding trouble.
Both women went to high school in Memphis where classes started at 7:45 a.m. Pruitt said her earliest class at UTC is 9 a.m.
"I grasp more ideas in class and more information," she said.
Dr. Anuj Chandra heads the Advance Center for Sleep Disorders, with offices here and in Cleveland, Tenn., and Trenton, Ga.
"As a society, we're all sleep-deprived," Chandra said in an interview before the lecture. He called Carskadon's research pinpointing a biological source for teen sleep patterns "groundbreaking."
Before scientists discovered this proof, many just assumed teens were lazy, he said.
Chandra's advice to parents is to set limits early, by children's age 9 or 10, to set up good habits.
"No TV in the bedroom, cellphones are turned off before bed," he said.