Occupational characteristics included the current number of employees, sector (public or private), occupation type, employment status, shift work, and working hours. Organizations were classified into 2 groups: those with up to 300 employees and those with more than 300 employees. Privately owned companies were classified as private-sector organizations, while central and local government offices; public institutions; and state-owned schools, hospitals, and universities were classified as public-sector organizations. Occupation types were categorized as white collar (e.g., supervisors, professionals, mechanics, semiprofessionals, and office workers) or service/sales workers (e.g., service workers; sales workers) or blue collar (e.g., skilled workers in agriculture, forestry and fishing; technicians; related technical workers; device or machine operation and assembly workers, and simple laborers) occupations. Employment status was classified as permanent or temporary, and shift pattern (shift work or non-shift work) was included as a variable.