Work partners Jon Chintanaroad (left) and Mike Prestano are all smiles now, but founding a tech startup together threatened their friendship — and their business. April Dembosky/KQED hide caption

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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

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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

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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