Twice a year, Americans reset their clocks and lose an hour of sleep. The tradition may feel like a modern nuisance, but it began as a wartime policy during World War I. At 2 a.m. local time Sunday, ...

If you’ve ever heard someone say a meeting is at 1630 and then felt your brain do a small cartwheel, you have met the 24-hour clock. In the United States, we mostly live by the 12-hour clock, with a.m ...