Students take the annual College Scholastic Ability Test, or college entrance exam, at a high school in Seoul last November. Students face enormous pressure to do well on the test and get into a top university. Airplanes are grounded on the day of the test so they won't disturb the students. Ed Jones/AFP/Getty Images hide caption

itoggle caption Ed Jones/AFP/Getty Images

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

When it comes to an employee's mental health status, what does an employer need to know, or have a right to know? iStockphoto hide caption

itoggle caption iStockphoto

About twice a year, statistics suggest, a pilot somewhere in the world — usually flying alone — deliberately crashes a plane. The Germanwing flight downed last week may be one such case. But most people who fit the psychological profile of the pilots in these very rare events never have problems while flying. Patrik Stollarz/AFP/Getty Images hide caption

itoggle caption Patrik Stollarz/AFP/Getty Images

When combined with results of other neurological tests, and in the context of a thorough medical history, atrophy of the brain (shown here in an MRI scan) sometimes indicates Alzheimer's. Simon Fraser/Science Source hide caption

itoggle caption Simon Fraser/Science Source

Laury Sacks and her husband, Eric. The actress and writer developed frontotemporal dementia in her late 40s and died in 2008 at age 52. Courtesy of Eric Sacks hide caption

itoggle caption Courtesy of Eric Sacks