当选总统唐纳德·特朗普 (Donald Trump)正在准备他要在宣誓就职后几小时就发布的一系列行政令，在上任第一天就动用行政权力，推进他在边境、能源和政府改革方面的优先事项。

Modern life makes us tired, right? But research from societies in Africa and South America suggests people in the ancient world slept only 6.5 hours a night.

Modern life makes us tired, right? But research from societies in Africa and South America suggests people in the ancient ...