ISLAMABAD: Female registered nurses who work a rotating night shift for 5 years or more have a slightly higher risk of heart disease, according to a new study published in JAMA.

Shift work can disrupt social and biological rhythms, which may increase the risk of chronic disease. The National Sleep Foundation list a number of conditions that people who work shifts are more likely to experience, including cancer, metabolic disease, ulcers, and obesity, not to mention depression and reduced performance due to disrupted circadian rhythms.

The authors point out that since the risk only affected those who worked 5 years or more on rotating night shifts, and this was only 15% of all the participants, the absolute risk and public health impact of night work is relatively small.

There was evidence that the risk decreased after quitting shift work, and the longer the time lapse since quitting, the smaller the chance of CHD.

The authors also looked at whether shift work was associated with increased CHD risk in the absence of hypertension, hypercholesterolemia, and diabetes. The first NHS suggested a link but the second did not, implying that shift work entails a risk even in those without prior susceptibility.