Those with an education level beyond high school had a lower prevalence rate of alternative shifts compared to workers with less education. Among all occupations, protective service occupations had the highest prevalence of working an alternative shift (54%). One of the ways in which working alternative shifts can impair health is through decreasing sleep opportunities. Among all workers, those who usually worked the night shift had a much higher prevalence of short sleep duration (44.0%, representing approximately 2.2 million night shift workers) than those who worked the day shift (28.8%, representing approximately 28.3 million day shift workers). An especially high prevalence of short sleep duration was reported by night shift workers in the transportation and warehousing (69.7%) and health-care and social assistance (52.3%) industries. Industries It is estimated that 15-20% of workers in industrialized countries are employed in shift work. Shift work is common in the transportation sector as well. Some of the earliest instances appeared with the railroads, where freight trains have clear tracks to run on at night. Shift work is also the norm in fields related to public protection and healthcare, such as law enforcement, emergency medical services, firefighting, security and hospitals. Shift work is a contributing factor in many cases of medical errors. Shift work has often been common in the armed forces. Military personnel, pilots, and others that regularly change time zones while performing shift work experience jet lag and consequently suffer sleep disorders. Those in the field of meteorology, such as the National Weather Service and private forecasting companies, also use shift work, as constant monitoring of the weather is necessary. Much of the Internet services and telecommunication industry relies on shift work to maintain worldwide operations and uptime. Service industries now increasingly operate on some shift system; for example a restaurant or convenience store will normally be open on most days for much longer than a working day. There are many industries requiring 24/7 coverage that employ workers on a shift basis, including: Caregiver Direct support professional Customer service including call centers Data center and IT Operations Death care (medical examiner or coroner) Emergency services Police Firefighting Emergency medical services Entertainment Casino workers Health care Funeral workers Hospitality Logistics & transportation Railways Ship Crew Manufacturing Flight Test Military Mining Public utilities Nuclear power Fossil fuel Solar, wind, and hydro power Retail Telecommunications Television Radio broadcasting Security Weather See also Effects of overtime Fatigue