People who work from mid-afternoon into the wee hours of the night are liable to develop problems such as heartburn, stomach ulcers and constipation, new research shows.

In the study, evening workers tended to work longer hours and more night hours - from midnight to 5 am - and follow a more irregular schedule, study author Dr. Claire C. Caruso told AMN Health.

“As a consequence, the workers might have reduced opportunity for adequate sleep, or the combination of these work schedule characteristics might have led to disturbed sleep,” said Caruso. “Good sleep is associated with less gastrointestinal symptoms and other symptoms,” she added.

Alternatively, an irregular work schedule can disturb the body’s internal clock, which it uses to synchronize eating and digesting food, she said.

Finally, the evening shift may increase the risk of stomach and intestinal ills if it isolates workers from friends and family, causing stress and, as a result, GI problems.

Caruso, who is based at the National Institute for Occupational Safety and Health, completed the study while at the University of Michigan in Ann Arbor.

According to the U.S. Bureau of Labor Statistics, nearly 15 percent of Americans work full-time on evening, night, rotating, split or irregular shifts. Previous research has linked these work schedules to an increased risk of health problems, accidents and errors.

Among shift workers, gastrointestinal (GI) problems are one of the most common health complaints. To investigate the rate of GI problems among shift workers, Caruso and her team surveyed 343 auto factory workers in the U.S., asking about their rate of GI problems and work schedules. No one worked the night shift.

The investigators found that people working the evening shift - typically from 2:30 PM to 11 PM - reported more GI symptoms, which included nausea, indigestion, abdominal pain, loss of appetite and diarrhea. They also were three times more likely to say they had been diagnosed with a GI problem, such as a stomach ulcer, ulcerative colitis, or colon polyps, according to the report in the American Journal of Industrial Medicine.

Caruso explained that a good night’s sleep is associated with a host of other health benefits, including a strong system, better memory and improved mood.

People who work irregular or evening schedules should “recognize the importance of getting restful sleep every day,” she said.

Caruso recommended visiting the National Sleep Foundation’s web site at http://www.sleepfoundation.org/ for more information about good sleep hygiene.

SOURCE: American Journal of Industrial Medicine 2004;