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Work & Sleep: Making the Weight Connection

 

Focus on Obesity In The Workplace, CONDUIT Spring 2015

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Click here to view the full Spring 2015 issue (PDF).

By Angela Pirisi

Sleep is essential for good health, but for many people, work is a major factor that stands in the way, given the longstanding tradition of shift work and the trend of employees being accessible 24/7 via smart phones and tablets. The workplace, both in terms of psycho­logical demands (or work load) and the physical environment, seems to play a significant contributing role to sleep loss, which subsequently has a dele­terious effect on weight management. That’s because missing out on both the quantity and quality of sleep sets in motion biological and behavioural processes that lead to increased food intake, fat storage and physical inactivity.

While longer work hours and blurred lines between work and personal time are a harsh reality, employers must  try to mitigate the negative health  effects that these are producing in their workforce.

Dangers of sleep debt

More than 35% of Canadians have trouble sleeping or staying asleep, about 10% get less than six hours of sleep regularly and 30% don’t feel refreshed after sleep, says Dr. Cameron Mustard, president and a senior scien­tist at the Institute for Work & Health (IWH). “That’s an important number of workers whose performance is being affected by sleep,” adds Mustard,  who is also a professor in the Dalla Lana School of Public Health at the University of Toronto.

But how much is our sleep affected by work?

“Work interferes with sleep for many of us, periodically or regularly, and one of the most common work schedules that interrupts people’s rhythm of life is shift work,” says Mustard. While most Canadian workers have regular 9-to-5 schedules, certain occupations, like nursing, have a large proportion of the workforce (20% to 50%) on evening or night shifts.

According to data from Alberta  Human Resources and Employment, most accidents occur when people tend to need sleep—between mid­night and 6 a.m., and between 1 p.m. and 3 p.m. WorkSafeBC reports that the effects of sleep loss are similar to alcohol consumption: 17 hours awake is equivalent to a blood alcohol con­tent (BAC) of 0.05, 21 hours awake is equivalent to a BAC of 0.08 (legal limit in Canada) and 24–25 hours awake is equivalent to a BAC of 0.10.

Researchers have also been explor­ing links between sleep loss and chron­ic disease. According to a 2010 IWH report, shift workers run an increased risk of workplace injury, breast cancer and other cancers, heart disease and possibly gastrointestinal conditions and mental illnesses. Tucker and col­leagues (2012) found that shift work, which disrupts the body’s natural sleep cycle, increases the risk of metabolic syndrome, a cluster of medical condi­tions that promote heart disease, and includes diabetes, obesity, dyslipid­emia and hypertension [Chronobiol Int 2012; 29(5):549-555.].

From sleep loss to weight gain

Sleep loss affects weight by modifying eating behaviour, as well as metabolic factors, suggests Dr. Jean-Philippe Chaput, Assistant Professor of Pedi­atrics at the University of Ottawa and Junior Research Chair of the Healthy Active Living and Obesity Research Group at the Children’s Hospital of Eastern Ontario Research Institute. Chaput and colleagues (2014) recently reported on how restricted sleep may contribute to obesity [Physiol Behav (2014) 134:86-91].

There are many reasons, but the simplest one is increased food intake: “The more time we spend awake, the more time we spend eating,” explains Chaput. Sleep depri­vation has also been associated with an increased desire to eat via the stimulation of the food reward system in the brain, he adds. Sleep loss also affects hormones that trigger hunger: ghrelin and cortisol levels increase and leptin decreases, meaning an increase in appetite and energy storage and trouble achieving satiety. Sleep restriction is also asso­ciated with less physical activity, most likely due to fatigue, suggests Chaput.

What’s more, sleep loss contributes to abdominal weight gain. “Lack of sleep is a stressor, which leads to elevated cortisol—short sleepers have higher levels of cortisol at the end of the day—and a preferential deposition of fat in the abdomen,” says Chaput. “In addition, growth hormone levels fall with lack of sleep and that also con­tributes to visceral fat.” Thus, stress due to sleep loss affects the endo­crine system, which can modify weight gain and fat distribution. Besides its biological effects, stress also affects food and alcohol intake behaviours that ultimately bear down on BMI. Unfortunately, work-related stress is another growing reality that’s part of a vicious cycle—stress worsens sleep, and poor sleep increases stress.

According to the 2010 General Social Survey (GSS), 27% of Canadian workers report being highly stressed on most days. What this means for individuals who have obesity and/or trying to manage their weight is that sleep loss, modified by workplace demands, may compromise weight management. “Short sleepers may also be less compliant in following a diet plan,” says Chaput. “Ghrelin levels are higher in short sleepers and among those who are on diets. This increased ghrelin level contributes to more fat storage in the body.” Cha­put has been investigating whether extending sleep time can limit weight gain and facilitate weight management.

Minimizing the damage

The workplace has a significant im­pact on lifestyle and health, including employees’ eating patterns, physical activity levels and sleep behaviour. As far as mitigating the negative effects of work on sleep and, ultimately, health, what solutions should em­ployers consider to modify the work environment?

“Generally, most workplaces where people work between 8 p.m. and  6 a.m. don’t have policies and practices for recognizing fatigue or organizing schedules so that it’s optimal for work­ers and the worst aspects of shift work can be minimized,” says Mustard. He suggests that employers could do more but there’s insuffi­cient data, which makes it difficult to fully under­stand the effects of shift work on health. So the first step would be mon­itoring work schedules and employees health. 

Mustard says we need to collect more informa­tion about employees’ work hours and their health profiles as they relate to work schedules and sleep patterns. The IWH explored in a report how employ­ers might mitigate the health effects of shift work. Recommenda­tions included optimal schedule changes, such as forward and quickly rotating shifts, flexible working conditions and controlled exposure to light and dark.

Meanwhile, Chaput suggests that seven to nine hours of unbroken sleep is ideal in adults, but if it’s not possible, grabbing a power nap of 10 to 20 minutes can minimize fatigue during a long workday or night shift. Providing healthier food choices can help work­ers cope with potentially unhealthy eating behaviours in an obesogenic environment, he adds.

Chaput and his colleagues are work­ing on developing the world’s first  evidence-informed guidelines for healthy sleep in the hopes of estab­lishing some health parameters for Canadians and employers.