Night work can be detrimental to workers' health, and steps should be put in place to reduce the possible ill-effects, according to a report by an EU body. Shiftwork and Health, published by the Dublin-based European Foundation for the Improvement of Living and Working Conditions, and written and edited by Prof Alexander Wedderburn of Heriot-Watt University, Edinburgh, sees night work as going against what the body wants to do. Moreover, socially, night workers can be more isolated because they're awake while others sleep, which impacts on family and social life.

The foundation's European Survey of Working Conditions 1996 found that night workers reported more health complaints than day workers, particularly sleep-related problems, fatigue, stomach ache and irritability.

However, more than 90 per cent of night workers did not report any stomach problems, while irritability caused by work was reported by only 16 per cent.

Shiftwork and Health cites studies reporting fatigue, headaches, depression, gastrointestinal problems, cardiovascular diseases and stress among night workers, while some women report impaired reproductive function. A French study found that former shiftworkers or night workers in the 40-64 age range had "the worst health of all men of their age".

Ironically, current night workers were found to have fewer health problems, but Prof Wedderburn explains that this is due to the "healthy survivor" effect. "The remaining shiftworkers are more healthy because the people with health problems are no longer shiftworkers."

However, women night workers were found not to be as healthy as male night workers; nor did their future health outlook seem favourable.

Night workers are more likely to have a good attendance record than day workers, perhaps because people of poorer health have already left night work or due to greater pressure to avoid affecting colleagues' nights off, says the report.

The study found that the average state of health of a night worker was "clearly impaired" during their first five years.

Over the following 15 years "no specific symptoms develop" but after the first 20 years of night work health problems "seem to accumulate" and manifest themselves after about 40 years.

While night work can clearly cause health problems, it doesn't always or inevitably do so, the report said. Sleep deprivation can cause a person to be "a tired and dangerous worker" and can lead to gastro-intestinal disorders.

Night workers have been estimated as being "from two to eight times" more likely to develop a peptic ulcer. One study found that 25 per cent of night workers skipped lunch, while 64 per cent smoked, compared to 44 per cent of day workers.

Although caffeine is best avoided five hours before bedtime, night workers tend not to follow this guideline and so sleep less well.

Some studies show an increased risk of cardiovascular disease among night workers so their health should be regularly monitored to enable evasive action if early indicators of cardiovascular disease are found.

The report also looks at gender-specific women's problems, social problems and psychological problems. For instance, it cites studies which found that women who did night work complained of irregular cycles and menstrual pains.

Women night workers also tended to report more premenstrual discomfort. Women night workers may bear a higher risk of miscarriage. They have lower rates of pregnancies, and women on rotating or irregular shifts are more likely to suffer severe menstrual pains.

Some studies have also associated premature births and low birth weight with night work.

Since night work impacts on social life, workers sometimes organise sleep and meals in an unhealthy way to compensate. Relationships with partners and children can also suffer, which in turn can have repercussions on the night worker's mental health and on their families, the report says. It also lists conditions that should preclude night work, including severe gastro-intestinal diseases; insulin-dependent diabetes; severe thyroid pathologies; epilepsy requiring medication; depression; chronic sleep disturbances; and chronic heart diseases.

The report concludes that any health promotion campaign for night workers needs to be supported at all levels, from management and occupational health professionals to cooking staff and vending machine operators. [SBX]

The Shiftwork and Health edition of BEST 1/2000 is published by the European Foundation for the Improvement of Living and Working Conditions. It can be downloaded from the European Foundation website at: www.eurofound.ie jmarms@irish-times.ie