EDITORIAL CONSIDERATIONS AND POSSIBLE CONSEQUENCES OF SHIFT WORK

Shift work can be de®ned as a work schedule where at least 50 % of work is re-quired to be done outside of the hours of 8:00 A.M. to 5:00 P.M. [1], which engages approximately 25 % of the work force in many Western societies [2, 3]. Working outside the ªnormalº hours either by extended days or shift rotation has a historical background and has increased since the invention of electricity and the industrial revolution. It is an ubiquitous feature of present-day working, social, and family life. Shift work involves professionals in emergency health care, public safety (law en-forcement, ®re), transportation (aviation, rail, etc.), night service workers (restau-rants, shopping, entertainment, etc.), military operations personnel, and many in-dustrial plant employees. Apart from providing and maintaining the obvious demands of industrial growth, shift work also improves employment opportunities and income, facilitates ¯exibility for couples vis-aÁ-vis childcare and domestic life, satis®es individual preferences due to variations in lifestyle, and is often associated with a relaxed hierarchy in the workplace and may ameliorate time pressures. Fam-ily advantages are sometimes perceived but individual preference is often a majo