Now that the 24-hour economy is putting an ever-increasing mark on social life, the effects of the disruption of natural biological rhythms are becoming clearer. In addition to its effects on sleep, this article discusses its long-term health effects. Potential measures to reduce and counteract the adverse effects of working night shifts on general well-being, sleep and health are summarized; the roles of light and rhythm are explored. Further research into the health effects of working nights and unsociable shift patterns is indicated.