Rich people can afford to buy more sleep than poor people

In Rich do not rise early: spatio-temporal patterns in the mobility networks of different socio-economic classes, a group of transportation engineers analyze an open data-set about the commutes of people in the Colombian cities of Medellin and Manizales, concluding that the rich and the poor commute the furthest distances, but that the rich have much shorter commutes, thanks to private transport and superior routing, which translates to substantially more sleep for the wealthy. (more")