Many studies have shown regular shift work undertaken by nurses, doctors and others is linked to heart and metabolic disease.
“Rotational night shift duties in healthcare workers may have a negative impact on metabolic parameters”
This latest research, published in the journal Experimental Physiology, suggests it may be because working shifts has a negative impact on the way fat is broken down and sugar is used by the body.
Researchers at the University College of Medical Sciences at the University of Delhi looked at the way these key physiological mechanisms operate in health workers who do shifts and those who do not.
They studied two groups each made up of 20 male and female nurses, doctors and other healthcare workers aged 20 to 40 – all with normal blood sugar levels.
Those in the first group had not done a night shift in the past year or never worked nights.
Meanwhile, those in the second group did rotational night shift duties, working more than four nights per month for the past year.
Participants’ blood sugar levels were measured using an oral glucose tolerance test. After 12 hours of overnight fasting, they were given a high fat meal to see how the body coped.
Insulin and triglyceride levels were measured before and after the fasting period and then again after the meal.
The study said to be the first to look at “postprandial triglyceride metabolism” in night shift workers found a positive correlation between fat levels and measures of insulin resistance – when cells ignore instructions from the hormone to absorb blood sugar.
However, this pattern was not seen in people who did not work shifts.
It suggests working night shifts may have an impact on the way the body absorbs fat, which in turn may boost insulin resistance, increasing the risk of type 2 diabetes and cardiovascular disease.
“In conclusion, findings of this pilot study suggest that rotational night shift duties in healthcare workers may have a negative impact on metabolic parameters including postprandial triglyceride responses and insulin sensitivity,” said the study paper.
The study authors said these findings may help explain why working shifts is linked to increased risk of poor health.
“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,” they said.