Women who work night shifts might be at a higher risk for developing cardiovascular disease, new Canadian research suggests

Joan Tranmer, a nurse for 30 years who is now a full-time researcher and teacher, and a team of researchers from Queen's University in Kingston, Ont., found that approximately one in five middle-aged women who do shift work has at least three of the risk indicators for heart disease.

Tranmer presented her findings in Vancouver at the Canadian Cardiovascular Congress 2011, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.

"Just how shift work contributes to the development of such risk factors isn't clear," Tranmer said. "It is possible that the disruption of biological rhythms, sleeping, eating, and exercise patterns may be factors."

Risk factors

Five signs connected with metabolic syndrome — a group of risk factors that together increase the risk for stroke, coronary artery disease and Type 2 diabetes — are abdominal obesity, high blood pressure, elevated blood glucose, elevated triglycerides and low levels of high-density lipoprotein (HDL) cholesterol – also known as "good cholesterol."

The research looked at 227 women between the ages of 22 and 66 from two hospitals in southeastern Ontario. The women were nurses, administrative employees and lab and equipment technicians who all worked a range of shift rotations.

Within the group, 17 per cent had metabolic syndrome with three of the identified risk factors. High blood pressure was found in 38 per cent and most notable was that 60 per cent of participants had a high waist circumference (abdominal obesity). The greater the waist circumference, the higher the risk of developing heart disease, stroke and high blood pressure.

'We spend so many of our hours and days at work, it is important for employers and employees to create as healthy a work environment as possible — especially for shift workers.' —Dr. Beth Abramson

The study also said that the age of the workers and how long they had worked shifts contributed to their risk.

Shift workers are more likely to get less sleep and worry about spending less time with family compared to those who don't work shifts, according to a Statistics Canada survey.

Heart and Stroke Foundation spokesperson Dr. Beth Abramson said the findings raise the need to look more closely at workplace policies that encourage healthy behavior — since a healthy lifestyle can reduce the risk for these women by as much as 80 per cent.

"All women should manage their weight and other risk factors, and this study shows women working shift work especially need to be aware," Abramson said. "We spend so many of our hours and days at work, it is important for employers and employees to create as healthy a work environment as possible — especially for shift workers."

Over four million workers aged 19 to 64 worked something other than a regular day shift in 2005, according to Statistics Canada.