Why do people get bags under their eyes when they don't get enough sleep?

The film stars former professional wrestler Roddy Piper as a homeless laborer who falls in with a group of shantytown rebels who have invented special dark glasses that enable the wearer to see past the façade the aliens have constructed to prevent their detection. One of the film's more memorable scenes occurs when Piper's character dons the glasses for the first time, and notices that a billboard for what appears to be a computer company now simply blares the word "OBEY," while another billboard featuring a bikini-clad model urges the viewer to "MARRY AND REPRODUCE." He also sees that money bears the words "THIS IS YOUR GOD." The messages are, of course, meant to be subliminal, causing people to become complacent about solving societal problems, spend money, stay in debt, remain unemployed, and increase the population.