Obesity and Decreased Sleep Duration Increase Risk of Work-Related Injury

Work-related injuries continue to negatively impact the employee, the employer, and society as a whole. There are a variety of approaches to employee health, but many of these are reactive. While therapists play an integral role in rehabilitating an injury, much more can be done proactively to limit employee risk to injury. While we’ve previously discussed topics like non-recordable care, post-offer employment testing, and stress management as proactive ways to reduce injury or improve recovery, there are other factors known to contribute to work-related injuries. These factors include sleep deprivation and body mass index. These factors, while likely not top of mind for employers, do function as modifiable variables which can reduce the probability of injury.

Body mass index, or BMI, considers an individual’s height and weight and provides a quick reference value of an individual’s amount of body fat. Typically, when this value is elevated, it suggests that an individual may be overweight, and therefore may be at increased risk for certain health problems.¹ While many of us correctly assume that elevated BMI can contribute to health conditions like diabetes, high blood pressure, and heart disease,² we often fail to see a connection between elevated BMI and work-related injuries. While this may not seem obvious, the research continues to demonstrate this connection. Let’s explore a few recent research studies and examine the implications of elevated body mass index on work-related injuries.

1. A 2007 study of 2,221 employees revealed that 29% of these individuals experienced a work-related injury during the period of the study. Approximately 85 percent of these injured workers were classified as overweight or obese. The odds of injury in the highest obesity group when compared with the ideal body mass index group were 2.21x higher after adjustment for sex, age, education, smoking, physical demands of the job, plant process and location, time since hire, time in the job, and significant interaction terms.³ In short, after taking into consideration lots of other variables, the researchers were able to conclude that it was BMI alone that served as a significant contributing factor to workplace injuries.
2. A 2016 study in the Journal of Safety Research, which analyzed data over a 9-year period, was able to conclude that overweight and obese workers were 25% to 68% more likely to experience injuries than normal weight workers.⁴
3. Another 2016 study in the Journal of Occupational and Environmental Medicine, which also analyzed injury rates over a 9-year period, concluded that the prevalence of injury gradually increased as body mass index levels increased in most occupational and industry groups. The study’s conclusion was that overweight and obese workers were 26% to 45% more likely to experience injuries than normal-weight workers.⁵
4. Finally, a 2007 study published in the Archives of Internal Medicine, demonstrated a clear relationship between BMI and the rate of worker’s compensation claims. Employees in obesity class III (BMI >/=40) had 11.65 claims per 100 full time employees, while recommended-weight employees had 5.80 claims. Considering the other studies referenced above, this is not surprising. That said, this study took it a step further and assessed medical and indemnity costs, along with lost workdays. The results were staggering. Elevated BMI employees’ medical costs associated with claims were almost 7x more expensive, and their indemnity costs almost 11x more expensive, when compared to their recommended-weight counterparts. Furthermore, elevated BMI employees were out of work for 13x longer than their recommended weight counterparts.⁶

As outlined above, there is clear correlation between elevated BMI and increased risk of injury at work. So, what can employers do to reduce this risk factor? Afterall, in today’s competitive job market, most employers don’t have the luxury to pass on otherwise qualified candidates. While we plan to discuss a more holistic approach to Total Worker Health⁷ in upcoming blog posts, today’s discussion will focus on a singular action taken by employees (and encouraged by employers) to assist in weight management: adequate sleep.

The less you sleep, the more likely you are to eat. This is due, in part, to an elevated level of circulating endocannabinoids. The name of this chemical may sound familiar, as it’s very similar chemically to the drug cannabis. Decreased sleep (less than 7 hours/night), elevates the level of this chemical and results in the stimulation of appetite and one’s desire to snack. One study demonstrated that reduced sleep resulted in participants craving unhealthy, calorie-dense food. This resulted in an extra 600 calories consumed compared to when the participants were well rested.⁸ Think about that for a moment and consider the following: 1 pound of body weight equates to 3,500 calories. It could be argued that if study participants maintained the same poor sleep schedule, and continued to consume 600 additional calories/day, that they may gain over 1 pound of body weight/week. Extrapolate that out over months/years and the results can be profound.

If an increase in hunger stimulating endocannabinoids wasn’t already bad enough, sleep deprivation also results in changes to other chemicals associated with hunger: leptin and ghrelin. Leptin is a hormone associated with satiety (or feeling full/satisfied after a meal), and ghrelin is a hormone associated with promoting hunger. Unfortunately, when sleep is limited, an increase in ghrelin occurs simultaneously with a decrease in leptin. In short, the “I’m hungry” single in amplified while the “I’m full” signal is depressed. As you might imagine, this has significant implications for overeating and subsequent weight gain.⁸

Now you may be asking yourself, what direct control does an employer have over employee’s sleep schedule? In short, little to none. Outside of minimizing overtime and providing education, an employer is limited. But, as we’ll discuss in upcoming blogs, by approaching employee health from a Total Worker Health⁷ perspective, which includes educating and encouraging employees on healthy best practices, employers can indirectly influence employee behavior. This, along with other direct approaches (like developing health-enhancing policies, programs, and practices while redesigning the work environment for safety, health, and wellbeing), can serve to further minimize on-the-job injuries. Promoting a good night’s sleep can help employees manage their weight, which in turn can reduce the probability of injury.

1. “Body Mass Index (BMI).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 3 June 2022, https://www.cdc.gov/healthyweight/assessing/bmi/index.html.
2. “Assessing Your Weight and Health Risk.” National Heart Lung and Blood Institute, U.S. Department of Health and Human Services, https://www.nhlbi.nih.gov/health/educational/lose_wt/risk.htm#:~:text=Body%20Mass%20Index%20(BMI),-BMI%20is%20a&text=The%20higher%20your%20BMI%2C%20the,breathing%20problems%2C%20and%20certain%20cancers.
3. Pollack KM, Sorock GS, Slade MD, et al. Association between body mass index and acute traumatic workplace injury in hourly manufacturing employees. Am J Epidemiol. 2007;166(2):204-211.
   doi:10.1093/aje/kwm058
4. Gu JK, Charles LE, Andrew ME, Ma CC, Hartley TA, Violanti JM, Burchfiel CM. Prevalence of work-site injuries and relationship between obesity and injury among U.S. workers: NHIS 2004-2012. J Safety Res. 2016 Sep;58:21-30. doi: 10.1016/j.jsr.2016.06.001. Epub 2016 Jun 14. PMID: 27620931; PMCID: PMC5259819.
5. Gu JK, Charles LE, Fekedulegn D, Ma CC, Andrew ME, Burchfiel CM. Prevalence of Injury in Occupation and Industry: Role of Obesity in the National Health Interview Survey 2004 to 2013. J Occup Environ Med. 2016 Apr;58(4):335-43. doi: 10.1097/JOM.0000000000000670. PMID: 27058472; PMCID: PMC4922363.
6. Ostbye T, Dement JM, Krause KM. Obesity and workers’ compensation: results from the Duke Health and Safety Surveillance System. Arch Intern Med. 2007;167(8):766-773. doi:10.1001/archinte.167.8.766
7. Total Worker Health is a registered trademark of the US Department of Health and Human Services (HHS). https://www.cdc.gov/niosh/twh/default.html
8. Walker M. Why We Sleep – Unlocking the Power of Sleep and Dreams. Scribner; 2017.
9. “How a Lack of Sleep May Increase Calorie Consumption.” Sleep Foundation, 26 Apr. 2022, https://www.sleepfoundation.org/sleep-deprivation/lack-sleep-may-increase-calorie-consumption.