Study finds working the graveyard shift can have more serious health consequences than previously thought. New data should support better compensation.

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The News:

Night-shift work may wreak havoc with blood-sugar levels, a new study asserts. Researchers analyzed data on more than 270,000 people in the United Kingdom and found that those who worked irregular or rotating shifts that included night shifts were 44% more likely to have type 2 diabetes than those who worked only days.

“Shift work, particularly night shifts, disrupts social and biological rhythms, as well as sleep, and has been suggested to increase the risk of metabolic disorders, including type 2 diabetes,” said study co-first author Celine Vetter, Director of the University of Colorado’s Circadian and Sleep Epidemiology Laboratory, according to the Chicago Tribune.

The more often a person worked an irregular night shift, the greater their risk for type 2 diabetes, the findings showed. For example, working nights less than three times a month increased the risk by 24%, but working nights more than eight times a month increased the risk by 36%.

“Our study is one of the first to show a dose-response relationship, where the more often people work nights, the greater their likelihood of having the disease,” Vetter added in a university news release.

However, working a permanent night shift was not linked to an increased risk of diabetes. The study authors suggested that these people might adapt to a consistent night-shift schedule, or perhaps they were “night owls” who had a natural tendency to be awake at night.

About 15 million American workers have permanent night shifts, rotating shifts or shifts with irregular schedules, the study authors noted. If a person can’t avoid working nights, they may be able to reduce their health risks by eating a healthy diet, watching their weight, and getting enough exercise and sleep, Vetter advised.

The findings could not prove a cause-and-effect relationship between rotating shift work and type 2 diabetes. But, other recent studies have also found associations between these work schedules and heart disease, diabetes and cancer.

The new report was published online in February in the journal Diabetes Care.

Steve’s Take:

Right after law school I found myself working at the US Treasury Department weekdays and doing the “all-night” weekend show for local FM radio station WJMD. The nighttime gig was 11PM to 7AM Friday and Saturday. I had always wanted to be a “DJ” growing up, and when the opportunity arose, I grabbed it.

Little did I, or anyone else on a night-shift schedule, realize we were at a 44% higher risk to develop type 2 diabetes. If we had, we would’ve pounded (okay, tapped) on the GM’s desk, flung down the aforementioned study and demanded (okay, pleaded for) considerably more compensation than the day-shift crowd. After all, who wants a nearly double risk of type 2 diabetes?

Turns out other recent studies have found associations between such shift work and cardiovascular disease and cancer, but few have looked specifically how different work schedule characteristics impact risk.

For example, a study published in the American Journal of Preventive Medicine found that women who have worked rotating night shifts for five years or more not only experience shorter lifespans in general, but also have an increased risk of dying from cardiovascular disease. Those who have performed rotating shift work for 15 years or more are also more likely to die of lung cancer, says the Huffington Post.

In the AJPM study, a team of international researchers monitored approximately 75,000 female registered nurses in the US for 22 years through Nurses’ Health Study data, which included an interview with each nurse every other year. Defining rotating shift work as “working at least three nights per month in addition to days or evenings in that month,” the researchers asked the women how many years they had worked in this manner.

Of the women who worked rotating night shifts for more than six years, 11% experienced a shortened lifespan. Risk of death by cardiovascular disease jumped by 19% for those who worked this way for six to 14 years and by 23% for those who did so for 15 years or more. Women who worked rotating night shifts for more than 15 years also experienced a 25% higher risk of death due to lung cancer.

Previous research has acknowledged shift work’s many links to poor health: The World Health Organization deemed it a carcinogen in 2007 due to its repeated disruption of the body’s circadian rhythm, and it has also been associated with an increased risk for heart and brain problems. This AJPM study further reveals how important a role circadian rhythms play in cardiovascular health and tumor prevention.

Referring to the Diabetes Care study, Eva S. Schernhammer, MD, DrPH, an associate professor of medicine at Harvard Medical School and an associate epidemiologist at Brigham and Women’s Hospital said, “These results add to prior evidence of a potentially detrimental relation of rotating night shift work and health and longevity,” She added, “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 (e.g., chronotype) warrant further exploration.”

Night Shifts Worked Per Month vs No Night Shifts type 2 Diabetes Risk
< 3 nights/month 24% higher risk
3–8 nights/month 11% higher risk
> 8 nights/month 36% higher risk

(Courtesy of Medscape)

Perhaps not unexpectedly, the Diabetes Care study found that levels of physical activity also affected a worker’s risk of developing type 2 diabetes. For example, the risk of type 2 diabetes was “consistently higher” among workers who reported low levels of physical activity and who worked any night shift.

Steve's Take: If you work the #graveyardshift make sure you get the highest, hazardous-duty pay you can negotiate. Fact is, studies show you deserve it. Click To Tweet

In contrast, the risk of type 2 diabetes was only higher when workers with higher levels of physical activity reported work schedules that usually included night shifts.

“Our study findings represent another puzzle piece in this quest towards healthier work schedule design,” the researchers conclude.

 Bottom Line:

While it may be industry standard to pay an employee a shift differential for overnight work, according to the Fair Labor Standards Act (FLSA), it isn’t a federal requirement. The FLSA states:

“Extra pay for working night shifts is a matter of agreement between the employer and the employee (or the employee’s representative). The Fair Labor Standards Act (FLSA) does not require extra pay for night work. However, the FLSA does require that covered, nonexempt workers be paid not less than time and one-half the employee’s regular rate for time worked over 40 hours in a workweek.” (Ref:

Essentially, the FLSA provides that aside from overtime pay, employers are not required to pay employees additional pay for their work, abnormal schedule or not. Assigning an employee late hours is not grounds for additional pay.

Perhaps now it should be.

Government employees whose salaries are dictated by the Federal Wage System are entitled to a night shift differential when the majority of their regularly scheduled, non-overtime hours fall between 3PM and 8AM.

The amount of that bonus depends on when the employee works the majority of their hours. For example, a shift that goes from 3PM to midnight would earn them 7.5% on top of their base pay, and a shift that goes from 11PM to 8AM would net them an extra 10%.

Working the graveyard shift (pun intended) isn’t for everyone. But if you want to make more money, it might be for you. Just take this Diabetes Care study and get the highest, hazardous-duty pay you can negotiate. Fact is, you deserve it.

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