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Health In A 24-Hour Society (p 999)

September 19, 2001

The increasing demand of many societies for people to work outside office hours could have negative influences on health, legal, and economic outcomes, suggest authors of a review article in this week's issue of THE LANCET.

20% of workers in urban societies work outside regular office hours. Shantha Rajaratnam and Josephine Arendt from the Centre for Chronobiology, University of Surrey, UK, emphasise how the desynchronisation of circadian wrhythms-common in shift-workers-has a detrimental effect on work performance and increases the risk of sleep disruption, gastrointestinal disorders, and cardiovascular disease. The authors compare the effects of shift work with jet lag, and comment that adaptation to a new circadian rhythm can be accelerated by carefully timed exposure to light or the hormone melatonin. However, they also caution that the increased risk of shift-workers to poor health outcomes will result in increased future litigation; they suggest that employers use current scientific knowledge about circadian-rhythm adaptation to develop effective working environments for shift-workers.

Shantha Rajaratnam comments: "Biological time is not only scientifically important, but it also greatly affects the productivity and health of a nation. The cost to the nation's health of working out of phase with our biological clocks is probably incalculable at present. In the short term, poor sleep, gastrointestinal problems, higher accident rate, and social problems are evident. Employers and individuals need to be aware of the major performance and alertness decrements associated with night activity and how to best manage and counteract them. It is worth noting that in a classic early experiment, forcing flies constantly to shift their clocks led to substantially lowered life expectancy. The same result was recorded in cardiomyopathic hamsters that had their light-dark cycle shifted on a weekly basis. Manipulation of human beings in the same way would, of course, be unethical. However, either by choice or by necessity, many of us are doing an uncontrolled experiment on ourselves."

Contact: Liz Morgan-Lewis, Marketing and Public Affairs, University of Surrey, Guildford GU2 7XH, UK; T) +44 (0)1483 683932; F) +44 (0)1483 689389; E) L.Morgan-Lewis@surrey.ac.uk

Lancet