Our increasingly 24/7, globalized work world demands that some people work at night, have extended work hours, or rotate between working night, day, and evening shifts. Nearly one-quarter of all workers have shifts that are not during the daytime, and more than two-thirds of these workers have problem sleepiness and/or difficulty sleeping. (NHLBI, 2005) In addition, nearly a third of Americans report working 10 hours or more each day. (NSF, 2008) Such extensive work hours can affect how much time workers have for sleep, as many on a limited time budget sacrifice sleep for needed leisure time, attention to domestic tasks, or multiple jobs.
Irregular or long hours put many workers at odds for acquiring enough quality sleep to function properly and operate machinery and vehicles safely. The drowsiness experienced by night shift workers can be especially dangerous. Not only are night-shift workers prone to serious driving accidents after their shifts end, but major industrial accidents, such as the Three Mile Island and the Exxon Valdez oil spill, have been caused, in part, by mistakes made by excessively sleepy workers on a night or extended shift. (NHLBI, 2005) In addition, night shift workers