It’s easy to complain about the 9-to-5 working life.
But shift workers probably have more reason to grumble.
New research has found that working shifts is linked to an increased risk of heart attacks and strokes, prompting experts to recommend that shift workers be regularly screened for cardiovascular disease.
The study — the largest of its kind — found that shift work was associated with a 23 per cent increased risk of heart attack, a 24 per cent increased risk of a coronary event and a 5 per cent increased risk of stroke.
In Canada, that would mean 1 in 14 heart attacks and 1 in 60 strokes are directly related to shift work, said the study’s primary author, Dr. Daniel Hackam, an internist at University Hospital, which is a part of London Health Sciences Centre.
For the study, shift workers are defined as those who do not have traditional daytime work schedules, including people who work regular evening or night schedules, rotating, split or on-call shifts and 24-hour shifts.
About 33 per cent of Canadian adults who are employed full-time are considered shift workers, according to a survey conducted by Statistics Canada in 2009-2010.
“Shift workers need to be vigilant about their cardiovascular health and their risk factors for cardiovascular disease, and these should be checked on an annual basis through their primary care provider,” said Hackam, who is also an associate professor of medicine at Western University.
Doctors, too, need to be aware of the association between shift work and cardiovascular events, he said.
“They should try to be diligent about aggressively modifying risk factors in shift workers and not just writing it off as a manifestation of an unhealthy lifestyle.”
Hackam said the risk factors that should be checked include cholesterol levels, blood pressure, weight and waist circumference, diet and level of physical activity. Stopping smoking is also important, he said.
Published Tuesday in BMJ (British Medical Journal), the research analyzed 34 studies that had previously investigated the links between shift work and cardiovascular health. The analysis included more than 2 million study participants.
In addition to the main findings, the researchers showed that working night shifts was linked to a 41 per cent increase in risk for coronary events.
However, they also found that shift workers did not have an overall increased risk of death from any cause when compared with those with traditional daytime schedules.
Dr. Andy Wielgosz, a senior spokesperson for the Heart and Stroke Foundation of Canada and professor of medicine at the University of Ottawa, said that although the meta-analysis “seems to point to a finding that cannot be ignored,” more research needs to be done to pinpoint what accounts for this link between shift work and major vascular events.
Previous research has suggested that working shifts raises blood pressure, prompts changes in metabolism and causes sleep deprivation, he said.
“One could envision how that could lead to heart attacks and strokes,” said Wielgosz, who did not participate in the study.
He also noted that shift workers are more likely to be from lower socioeconomic strata, which has been linked to an increased risk for poorer lifestyle habits such as smoking — something that could also increase their chance of having heart attack or stroke.
Both Wielgosz and Hackam said the findings should encourage industries that rely on shift workers to create healthier workplaces for their employees.