With a large population engaging shift work, ranging in sectors from healthcare to transportation, researchers have set out to understand the effects of working long hours on the overall health burden on the workforce.
Many studies have shown that shift work is associated with heart and metabolic diseases, but new research published in Experimental Physiology has clarified how shift work can have a long-term effect on the risk of heart disease and diabetes.
The study specifically suggested that shift work has a negative impact on the way a type of fat (called triglycerides) is broken down, as well as on the way sugar is utilized in our bodies.
Both of these increase the risk of heart disease and diabetes because they affect how our body processes sugar and fat.
How was the Study Conducted?
Researchers at the University College of Medical Sciences, University of Delhi conducted research on two groups of healthcare workers.
The first group included nurses, doctors and other healthcare workers aged 20 to 40 of both sexes who had not done night shift in the last year or ever and had normal blood sugar levels.
The second group was of the same professional background and age, but involved in rotational night shift duties (more than 4 nights duties per month at least for last one year) and had normal blood sugar levels.
Blood sugar levels were measured using an oral glucose tolerance test. Then, after 12 hours of overnight fasting, participants were given a high-fat meal.
Fasting insulin levels, and triglyceride levels, after fasting and after the meal, were measured in all of the study participants.
The results were compared between health care workers with and without night shift duties.
What were the Study Results?
The authors conclude that studies on the postprandial period demonstrate that in experimental conditions, abrupt or acute changes in sleep timing and work are followed by significantly altered postprandial glucose, insulin secretion, and lipid tolerance.
However, whether shift work results in altered postprandial triglyceride (PPTG) metabolism in the long term is not known.
In the study, researchers aimed to ascertain the association between PPTG and shift work in relation to cardiometabolic risks and to compare the PPTG response among healthcare workers with and without night shift duties.
Twenty healthcare workers with rotational night shifts (group 2) and 20 age‐ and sex‐matched healthcare workers who had not done night shift duty in the past 1 year or ever (group 1) were recruited. Only subjects with normal glucose tolerance were recruited.
A standardized fat challenge test was done in all study subjects. The postprandial triglyceride area under the curve showed overall a significant positive correlation with fasting insulin and homeostatic model assessment of insulin resistance and in group 2.
In conclusion, the findings of this study suggest that rotational night shift duties in healthcare workers might have a negative impact on metabolic parameters, including PPTG responses and insulin sensitivity.
“This study gives us a better understanding of why shift work is associated, in the long-term, with heart and metabolic diseases, helping us work towards reducing the incidence of heart disease, diabetes, and obesity in the future,” said lead author S.V. Madhu.
The research has been published in The Physiological Society.
- The Physiological Society. Shift work increases diabetes and heart disease risk. EurekAlert! (2019, April 2). Retrieved: https://www.eurekalert.org/pub_releases/2019-04/tps-swi040219.php