About 40 percent of high schools start before 8 a.m., which contributes to chronic sleep deprivation among teens, according to the American Academy of Pediatrics. Chris Waits/Flickr hide caption

itoggle caption Chris Waits/Flickr

Dr. Donald Brown inoculated Kelly Kent with the HPV vaccine in his Chicago office in the summer of 2006 — not long after the first version of the vaccine reached the market. Charles Rex Arbogast/AP hide caption

itoggle caption Charles Rex Arbogast/AP

Amy Myers talks with her son Kamron, 18, in the backyard of their home in Boise, Idaho. She has found raising a teenager to be extremely stressful. Kyle Green for NPR hide caption

itoggle caption Kyle Green for NPR

A worker cleans the home of a hoarder in Las Vegas. Teens may not have the time to accumulate this much stuff, but they still have symptoms. AP/City of Las Vegas via Las Vegas Review-Journal hide caption

itoggle caption AP/City of Las Vegas via Las Vegas Review-Journal

Singer Ke$ha performs during the iHeartRadio Music Festival at the MGM Grand Garden Arena in Las Vegas in September. Ethan Miller/Getty Images hide caption

itoggle caption Ethan Miller/Getty Images