Work-to-rule and holidays, and police officers refusing to issue citations. Refusal to work overtime, travel on duty, or sign up to other tasks requiring employee assent are other manifestations of using work-to-rule as industrial action. It was described by Sir John Donaldson as a decision to "Give the rules a meaning which no reasonable man could give them and work to that." Sometimes the term "rule-book slowdown" is used in a slightly different sense than "work-to-rule": the former involves applying to-the-letter rules that are normally set aside or interpreted less literally to increase efficiency; the latter, refraining from activities which are
Shift work may be due to alterations in circadian rhythm: melatonin, a known tumor suppressor, is generally produced at night and late shifts may disrupt its production. The WHO's International Agency for Research on Cancer listed "shiftwork that involves circadian disruption" as a probable carcinogen. Shift work may also increase the risk of other types of cancer. Shift work also increases the risk of developing cluster headaches, heart attacks, fatigue, stress, sexual dysfunction, depression, dementia, obesity, metabolic disorders, gastrointestinal disorders, musculoskeletal disorders, and reproductive disorders. Shift work also can worsen chronic diseases, including sleep disorders, digestive diseases, heart disease, hypertension, epilepsy, mental