Shift work may have negative impact on long-term health

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It's safe to say Una Ferguson is a night person. For nearly 50 years, the Ottawa-based nurse has worked the overnight shift, taking care of patients and dealing with medical emergencies while most everyone else was asleep.

When her children were small, working nights enabled Ferguson to see the kids off to school in the morning and, later, help them with homework before she headed into work. Now, the 68-year-old says she simply enjoys the rhythm of those late nights, even now as a part-timer, and that she wouldn't have it any other way.

"The people who work permanent nights, you'll find, are a group of their own," Ferguson says. "You sort of have your own little family at night."

Of course, Ferguson, a medical professional, knows night shifts also have a worrisome downside: Research is showing that people who work at night are more likely to suffer a host of serious ailments. "It does play havoc with your health," she says.

Experts who study sleep patterns and shift work are increasingly concerned that people who go against the body's built-in biological clock for long periods face real dangers. The research is still in its infancy, but experts say that disrupting the body's natural sleep cycle may contribute to higher incidences of cancer, diabetes, mental-health disorders and heart disease.

Moreover, those risks aren't confined to people who work overnight. Employees who work late-evening shifts or overnight for a few weeks or months at a time can also face those medical consequences. It's even possible that professionals working extra-long hours could experience health effects.

So, for the health system, those risks, if proven, could have a massive impact because of the number of people whose jobs power our 24-hour society. According to a 2005 report from Statistics Canada, nearly four million Canadians worked unconventional hours, and the trends suggest that number has climbed since then.

Dr. Frank Scheer, director of the medical chronobiology program at Brigham and Women's Hospital in Boston and assistant professor at Harvard Medical School, is on the forefront of understanding how shift work can affect long-term health. He and his colleagues have discovered that the body's circadian rhythm – the impulses that regulate when we sleep and wake up – is distinct from the body clock. It's a surprisingly important distinction.

According to Scheer, the body clock controls a number of important physiological functions, like how the metabolic and cardiovascular systems operate. His research has shown that even when people are in bed in a dark room, their bodily impulses to eat at regular meal times during the daylight hours kick in.

What that means is that people who work at night are not only disrupting their natural sleep and wake cycle, they are also interfering with a whole host of other bodily functions and processes. Scheer compares it to having your brain in one time zone and your internal organs in another. And constantly disrupting those intricate systems, which have evolved over millions of years, seems to have real consequences.

"A lot of functions in the body are influenced by night and day," says Dr. Paul Demers, director of the Occupational Cancer Research Centre and senior scientist at Cancer Care Ontario.

Working odd hours can also make it difficult for people to get enough exercise, eat healthy meals or get enough sleep, which add up to poor health in the long run.

A study published in January by the American Journal of Preventive Medicine found that women who work on rotating night shifts for as little as five years face a higher risk of premature death and heart disease. The research also found that women who work those shifts for 15 years or more have an increased lung cancer risk.

In December, the United Kingdon's Health & Social Care Information Centre released a report that found people who work outside the hours of 7 a.m. to 7 p.m. are more likely to suffer mental-health problems, be obese and have Type 2 diabetes.

Another study, published in the Occupational and Environmental Medicine journal in November, found that shift work was linked to cognitive impairments such as taking longer to process information and having trouble with short- and long-term memory. And the longer a person did shift work, the more pronounced those cognitive issues became. The researchers say people who worked shifts for more than a decade aged their brains at a faster rate than day workers.

In 2007, the International Agency for Research on Cancer deemed shift work a probable carcinogen. And in 2013, Canadian researchers published a study that found women who worked night shifts for 30 or more years were twice as likely to develop breast cancer.

There are still so many unanswered questions about when shift work starts to become a health risk, because it is so difficult to study. Cancer, for instance, takes years to develop, and it's often difficult to pinpoint a single cause. For example, although studies involving nurses show a clear link between long-term night-shift work and disease, it is difficult to figure out how great the risks are, not to mention how long a person can be exposed to odd-hour shifts before problems creep in.

"Could you imagine if, 10 years from now, we realize that this is a major risk, how horrified everyone would be?" says Dr. Lois Krahn, a sleep-medicine specialist at the Mayo Clinic in Scottsdale, Ariz. "I don't think we fully understand the magnitude of it."

Ferguson says she has long been aware that decades spent waking, eating, working and sleeping on the opposite schedule could pose serious health risks. So, for many years, she has been careful to bring healthy snacks to work to avoid binging on coffee and junk food. She's also dedicated to yoga and meditation to relieve stress and help keep her healthy.

"You're on a different time zone than everybody else," she says. "We're in the medical profession; we realize the risks. However, what you can do is counter some of the risks."

So what can other shift workers do? For starters, they need to get sleep – a full "night" of restorative rest – when their shift is over, says Dr. M. Safwan Badr, past president of the American Academy of Sleep Medicine. So many shift workers he sees are sleep-deprived because it can be difficult to sleep during the day, and there's the temptation to be awake with the rest of the world.

But sleep is more important, so pull down the shades and shut out the world for eight hours, says Badr, who is also chief of the division of pulmonary, critical care and sleep medicine at Detroit's Wayne State University School of Medicine.

Dr. Demers, the senior scientist at Cancer Care Ontario, says more research is needed into ways of minimizing the impact of unavoidable disruptions. Possible solutions could involve different lighting or reduced shifts at night to help people cope.

"The problem is we really live in a 24-hour society now. You simply can't turn back very easily."