To sleep, perchance to consolidate important connections in far-flung parts of the brain. Alberto Ruggieri/Illustration Works/Corbis hide caption

itoggle caption Alberto Ruggieri/Illustration Works/Corbis

Marco Rubio celebrates onstage with his family in 2010 after winning his U.S. Senate seat in Florida when he was just 39 years old. Now, he's expected to embark on a run for president. Alan Diaz/AP hide caption

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Re-enactors re-create the Battle of Appomattox Court House as part of the 150th anniversary of the surrender of the Army of Northern Virginia at Appomattox Court House. Steve Helber/AP hide caption

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A "getaway selfie," as Mokhtar Alkhanshali calls it: Alkhanshali (left) makes his way across the Red Sea with this boat driver — and without navigation equipment. Mokhtar Alkhanshali hide caption

itoggle caption Mokhtar Alkhanshali

Dr. Raj Mangrulkar and medical student Jesse Burk-Rafel at the University of Michigan Medical School. Good communication skills, teamwork and adaptability will help doctors thrive through swift changes in medical science, Mangrulkar says. Leisa Thompson/Courtesy of University of Michigan Medical School hide caption

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For someone 2.5 inches shorter than average, the risk of coronary artery disease increases by about 13.5 percent, scientists found. PW Illustration/Ikon Images/Corbis hide caption

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Fields of carrots are watered March 29, 2015, in Kern County, Calif. Subsidized water flowing in federal and state canals down from the wet north to the arid south helped turn the dry, flat plain of the San Joaquin Valley into one of the world's most important food-growing regions. Frederic J. Brown/AFP/Getty Images hide caption

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Joshua Haggmark, Santa Barbara's water resources manager, is in charge of getting the city's desalination plant back online. Becky Sullivan hide caption

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Secretary of Energy, Ernest Moniz, left, and Secretary of State, John Kerry wait for the start of a trilateral meeting at an hotel in Lausanne in March. Brendan Smialowski/AP hide caption

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A rabbi (center) supervises the production of Passover matzos at the Streit's factory on New York's Lower East Side, circa 1960s. This Passover will be Streit's last one at the landmark location. AP hide caption

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A spread from Enchanted Forest: An Inky Quest & Coloring Book by Johanna Basford. Sam Brill/Courtesy of Laurence King Publishing hide caption

itoggle caption Sam Brill/Courtesy of Laurence King Publishing

"We must try as best we can to balance isolation and engagement, pressure and incentives, so that human rights and dignity are advanced over time," Obama said five years ago, accepting the Nobel Peace Prize. Mark Wilson/Getty Images hide caption

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Homeowners sit in a conference room in Detroit's Cobo Center while waiting for their cases to be heard to avoid foreclosure from tax debts in Detroit on Jan. 29. This year, Wayne County officials sent out 62,000 foreclosure notices to city homeowners behind on property taxes. Paul Sancya/AP hide caption

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Retired agent Michael Vigil on a search and destroy operation in the Colombian jungle. "As an undercover, you're basically kind of an independent operator ... and it's very addictive." says Laura Brodie, a criminal and forensic psychologist. Courtesy Michael Vigil hide caption

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Melinda Townsend-Breslin holds a photo showing her and her mother standing in the parking lot of a favorite thrift store in 2013. William DeShazer for NPR hide caption

itoggle caption William DeShazer for NPR

A 2008 view of the leading edge of the Larsen B ice shelf, extending into the northwest part of the Weddell Sea. Huge, floating ice shelves that line the Antarctic coast help hold back sheets of ice that cover land. Mariano Caravaca /Reuters/Landov hide caption

itoggle caption Mariano Caravaca /Reuters/Landov

Michael Bolla and Sally Singer lift Leon Anders using a ceiling lift and sling at the VA Hospital in Loma Linda, Calif. The VA system is among a very small number of hospitals that have installed equipment and provided proper training so their nursing staff can avoid physically lifting and moving patients themselves. Annie Tritt for NPR hide caption

itoggle caption Annie Tritt for NPR