A new study from a group at Queen’s University has shown that one out of five middle-aged women doing shift work had at least three of the five signs of metabolic syndrome – which together increase your risk of heart attack and stroke. Female shift workers may face higher heart risks – Health – CBC News.
The group lead by Joan Tranmer studied 227 women between the ages of 22 and 66 who worked as nurses, technicians or administrative employees. 17 per cent of those women had at least three of the risk factors for metabolic syndrome. In their paper in Circulation in 2004, Grundy et al provide the American Heart Association criteria for metabolic syndrome (these are the risk factors and the level above which the test result is a problem):
“Abdominal obesity, given as waist circumference*†
Men102 cm (40 in), Women88 cm (35 in)
Triglycerides 150 mg/dL
HDL cholesterol
Men 40 mg/dL
Women50 mg/dL
Blood pressure130/85 mm Hg
Fasting glucose110 mg/dL”
Apart from the 17% that had three risk factors, 38% of the study participants had high blood pressure and 60 percent had abdominal obesity.
This study doesn’t directly look at the possible mechanisms by which shift work causes these problems – but as someone that does shift work with some on-call shifts lasting more than 24 hours, I can tell you that I believe this conclusion. There is a large body of research on shift work and it’s clear that it causes disturbances in sleep patterns which is harmful in of itself, as well as impacts family life, relationships, ability to exercise routinely, diet and a number of other issues. Overnight shifts can exacerbate migraines in those who have them. Overall, overnight shift work is very challenging physically and appears to be detrimental to the health of shift workers.
If you want to read more about shift work and measures that you can take to minimize its impact (such as techniques for improving sleep and dietary patterns), I found a good publication from the Occupational Health Clinics for Ontario Workers, Inc. (OHCOW – no, I didn’t make that acronym up!) called “Shiftwork: Health effects & solutions”. It’s located at http://www.ohcow.on.ca/resources/handbooks/shiftwork/shiftwork.pdf. Check it out! They have other resources about occupational safety and ergonomics here: http://www.ohcow.on.ca/resources/index.html