Hazards of working round the clock go far beyond permanent jet-lag feeling

Fri, Nov 12, 2010, 00:00

WE LIVE in a 24-hour world where services are available around the clock. Yet people forced to work in this environment are as a result more prone to diseases, including cancer and diabetes.

The difficulties are caused when we break away from our internal day-night clocks, a timekeeping system built after millions of years of evolution, and begin working at times when we would ordinarily be asleep.

Just how hazardous shift working can be and what can be done about it were under discussion last night at a talk by Dr Andrew Coogan, a lecturer in the department of psychology at NUI Maynooth, part of the ongoing Science Week Ireland.

He described how there was an ongoing conflict between societal demands for shift-work and ordinary human physiology. One in five people is expected to undertake shift work, equal to about 200,000 to 400,000 workers in Ireland, or 22 million in the US, he said during an interview before the talk.

“It is very important given the number of people involved in shift work that we know the health implications involved,” he said yesterday.

The health risks of shift work were well documented, he added. Shift workers have a higher incidence of diabetes, obesity, gastrointestinal upset and cardiovascular disease.

Certain cancers are also more common in shift workers, he said. “The WHO [World Health Organisation] classified shift work as a probable carcinogen in 2007,” he said. Cancer risk for shift workers was between 30 per cent and 80 per cent higher, depending on the type of cancer. “The essential problem is the conflict of shift work with our inbuilt physiology.”

Our bodies rely on sunlight to set our internal circadian clocks. Our metabolism automatically responds to the demands of the clock: for example, beginning to secrete digestive juices in anticipation of a morning meal, and shutting down digestion and other metabolic processes before it is time to go to bed.

Air travel between time zones can upset the clock, delivering unpleasant jet lag. Sunlight resets the clock in a few days, but shift work seems to block this readjustment. “The internal clock does not adjust to the shift schedule. It is like being permanently jet lagged,” Dr Coogan said.

“We should view shift work as a necessary evil,” he added, but try to develop ways to reduce its impact. One discovery relates to rotation of shift work patterns. Workers found it easier to work a morning, then an evening and then a night shift in that order, rather than the reverse.



Inside a PC:Take apart the pieces of a computer to see how they work. 8.30pm, TOG hackerspace, Dublin. Entry free; for more see www.tog.ie/events

Art and climate change exhibition and conference:see the work of international artists who worked in Donegal creating work on the theme of art and climate change. Regional Culture Centre, Letterkenny, 9.30am. Admission is free


Cosmos at the Castle:learn about the universe at exhibition on recent discoveries of extreme life forms on Earth and implications for life in outer space. Blackrock Observatory, 10am-5pm

Children’s workshop:Talks and tricks on astronomy and crafts for children aged 8 and over at the Caherciveen Library, Kerry from 3-5pm. Hosted by South Kerry Astronomy Cosmology Group. Entry is free