Posts Tagged ‘cvd’

Night Shifts Upset Sleep, Up Heart Death Risk

Night shift work not only disrupts sleep patterns but also increases the risk of cardiovascular disease (CVD) and lung cancer deaths, according to one of the largest prospective cohort studies worldwide with a high proportion of rotating night shift workers and long follow-up time.

“Women working rotating night shifts for more than 5 years have a modest increase in all-cause and CVD mortality.

Those working more than 15 years of rotating night shift work have a modest increase in lung cancer mortality.

These results add to prior evidence of a potentially detrimental effect of rotating night shift work on health and longevity,” report researchers led by Eva S. Schernhammer, MD, DrPH, Associate Professor of Medicine, Harvard Medical School, and Associate Epidemiologist, Department of Medicine, Brigham and Women’s Hospital, Boston.

There is substantial biological evidence that night shift work enhances the development of CVD.

In 2007, the World Health Organization classified night shift work as a probable carcinogen because of circadian disruption.


Sleep and the circadian system play an important role in cardiovascular health and anti-tumor activity.

The circadian system and its prime marker, melatonin, are considered to have anti-tumor effects through multiple pathways — including antioxidant activity, anti-inflammatory effects, and immune enhancement — and they exhibit beneficial actions on cardiovascular health by enhancing endothelial function, maintaining metabolic homeostasis, and reducing inflammation, the researchers noted.

“Direct nocturnal light exposure suppresses melatonin production and resets the timing of the circadian clock,” they stated.

“In addition, sleep disruption may also accentuate the negative effects of night work on health.

Taken together, substantial biological evidence supports the role of night shift work in the development of poor health conditions, including cancer, CVD, and ultimately, mortality.”


Using data from the Nurses’ Health Study, the international team of researchers analyzed 22 years of follow-up of nearly 75,000 women.

Night shift information was collected in 1988.

Rotating shift work was defined as working at least 3 nights per month in addition to days or evenings in that month.

The investigators found that working rotating night shifts for more than 5 years is associated with an increase in all-cause and CVD mortality.

Mortality from all causes appeared to be 11% higher for women with 6 to 14 years or more than 15 years of rotating night shift work.

CVD mortality appeared to be 19% and 23% higher for those groups, respectively.

There was no association between rotating shift work and any cancer mortality, except for lung cancer in those who worked the night shift for 15 or more years (25% higher risk).

“A single occupation (nursing) provides more internal validity than a range of different occupational groups, where the association between shift work and disease outcomes could be confounded by occupational differences,” the researchers noted.

“To derive practical implications for shift workers and their health, the role of duration and intensity of rotating night shift work and the interplay of shift schedules with individual traits (eg, chronotype) warrant further exploration,” they added.

The researchers published their results in the January 5, 2014 issue of the American Journal of Preventive Medicine.

Polycystic Ovaries Linked to Pregnancy Problems and Heart Disease

Polycystic ovary syndrome (PCOS) is one of the most common causes of women not ovulating and can lead to fertility problems.

PCOS has also been linked to pregnancy problems and heart disease.

Women with the condition typically have small cysts around the edge of their ovaries.

Symptoms include irregular periods, problems with ovulation, weight gain, and excessive hair growth.

Women with PCOS are also more likely to have fertility treatment.

A new Swedish study just reported online in the British Medical Journal indicates that women with PCOS are at increased risk of pregnancy complications, regardless of whether they are undergoing fertility treatment.

The nationwide study on 3,787 births among women with PCOS found these women were 45% more likely to experience pre-eclampsia (pregnancy–induced high blood pressure) and were more than twice as likely to give birth prematurely or to develop diabetes while pregnant.

Fertility is not the only health consequence these women face, however.

PCOS has been associated with an increased risk for cardiovascular disease (CVD), the leading killer of women and men alike.

PCOS has been associated with increases in artery-clogging triglycerides (fats) and insulin resistance, which boosts the chances for diabetes, a risk factor for heart disease.

“Some women need intervention based on existing guidelines, either to control their blood sugar to head off diabetes, or reduce their cholesterol to moderate the risk of premature heart disease.

For the rest, it’s a matter of treating each woman based on their individual needs,” said Sarah Berga, MD, former Chair of the Department of Gynecology and Obstetrics at the Emory University School of Medicine, at the “The Physiology of Cardiovascular Disease: Gender Disparities” conference held earlier this week at the University of Mississippi in Jackson.

“We know that PCOS puts these women at risk for CVD-related disease, but we do not yet understand the extent to which it does so.”

Experts recommend that women with PCOS be periodically screened for diabetes and treated for it if they meet certain formal criteria.

However, drug treatment to forestall diabetes has not been endorsed and it has not been established that giving women with PCOS metformin will delay or prevent diabetes.

Metformin is an oral drug used to manage diabetes, either alone or in combination with sulfonylureas or other agents.

Fertility experts often prescribe metformin to treat PCOS.

To identify whether an infertile woman who has PCOS will benefit from metformin, simple tests are performed to see whether she has insulin resistance, says Zev Rosenwaks, MD, director and physician-in-chief of the Center for Reproductive Medicine at the Weill Cornell Medical College in New York.

“If she does, then I prescribe metformin,” says Dr. Rosenwaks.

“Over 2 to 3 weeks, she slowly builds up to the usual dose of 500 milligrams of metformin 3 times daily or 850 milligrams twice daily with meals.”

If the woman does not start ovulating regularly over the next 6 to 8 weeks, then he initiates treatment with the ovulation-stimulating drug clomiphene.

About three-quarters of women with PCOS who are not ovulating will ovulate on clomiphene at some dosing level, and about half will become pregnant.