Lack of sleep, diet put shift workers at risk

Work with employee, employer to minimize risks

Technology and transportation have made the United States a 24-hour society, with many manufacturers, services, and utilities operating 'round the clock, either because the services are required at all times, the production process cannot be interrupted, or it makes financial sense to operate continuously.

To keep this perpetually moving society operating requires workers, and according to the U.S. Department of Labor's Bureau of Labor Statistics (BLS), more than 8 million American adults work in the evening, at night, or rotating or irregular shifts. For those people, sleeping at night and working during the day is a rare occurrence, and one that can have considerable effects on their health.

In humans, the desire to sleep is strongest between midnight and 6 a.m. Not surprisingly, the National Sleep Foundation says surveys of night shift workers reveal that 10% to 20% report they doze off on the job. Some shift workers are able to alter their internal, or circadian, clock to allow them to get a healthy amount of sleep in the daytime, so that they are alert and at full wakefulness throughout their night shift. But for many people, the pull of the body's natural wake/sleep cycle is difficult to alter, resulting in not enough sleep during the day, sleepiness during their evening or night work shifts, and a gradual deterioration in health.

Even day shift workers can have difficulty getting the eight to nine hours of sleep recommended for healthy adults; in shift workers, chronic sleep debt is a common problem that not only results in fatigue, but can contribute to health problems and safety risks.

"We have long known that long work hours, high fatigue levels, and work schedules that fail to account for human physiological needs are linked to a 20% increased rate of workers' compensation claims among facilities with extended-hours operations," according to Kirsty Kerin, PhD, shift work management specialist with Circadian Technologies.

Kerin co-authored a study for Circadian, "Ergonomics Risks, Myths, and Solutions for Extended Hours Operations" (available at, which presents findings that relate work schedules with ergonomic injuries and musculoskeletal injuries.

The Circadian report found that in 12,500 shift workers surveyed, 30% of men and 41% of women reported chronic or frequent back pain. A smaller percentage reported suffering wrist pain. The report's authors also speculate that sleep deprivation in shift workers who don't get a full night's sleep could make them prone to increased risk of ergonomic injury, and slows recovery time when there is an injury.

Helping shift workers stay healthy

Sleep experts and occupational health professionals agree that there is no one perfect shift work schedule that works for all employees in all settings. Many suggest that night shifts (usually 11 p.m. to 7 a.m.) should not be permanent, and that rotating shifts are healthier than extended periods of night work. Others say frequent juggling of day/night schedules carries its own health implications.

Circadian Technologies advise there are measures that workplace health and safety managers can take to help make shift workers safer and more productive:

  • Educate managers and shift workers about the need for adequate sleep and the warning signs of sleep debt and fatigue;
  • Install bright lights in work areas to "trick" the body into being awake and alert. Encourage shift workers to use dim lighting and light-blocking window coverings when they return home to sleep;
  • Encourage employer to provide healthy food choices in vending machines;
  • Caution shift workers about driving when fatigued. Encourage the use of carpools and public transportation.

Both OSHA and NIOSH warn employers to be sure safety training and refreshers are scheduled to cover all shifts. Surveys have indicated that while shift workers may be the employees who most need safety training because of the risks of working at night or while fatigued, their training sometimes lags behind that of workers on "normal" shifts.

OSHA requirements do not address shift workers differently from other workers, but mandates that workers be given the same protections and safety measures, regardless of what time of day they are on the job.

"Involving employees in schedule selection, training workers on managing the work-life demands of working extended hours, and revisiting workplace policies such as break rules and rest periods can significantly decrease the risk of costly accidents and injuries," the authors of the Circadian study write.

Excess weight means added risk

People whose work shifts cause them to get inadequate sleep might be hurt even more if they are overweight or obese. According to Robert D. Vorona, MD, people with high body mass indexes (BMIs) sleep less than their peers with normal BMIs. Consequently, they are more prone to excessive daytime sleepiness and at increased risk for work-related injury and automotive accidents.

Vorona, of Eastern Virginia Medical School in Norfolk, and colleagues examined subjects' total sleep time in relation to their BMI, and found that as BMI increased, total sleep time decreased, and the difference was greater when the subjects were night-shift workers. On average, the difference in total sleep time between subjects with normal BMIs and patients with normal BMIs was about 16 minutes per day; when the subjects were night-shift workers, the difference was 42 minutes. (For a complete report on the study, which appears in Arch Intern Med 2005; 165:25-30, visit

Because dining options are fewer during the late-night shift than during the day, shift workers might find themselves eating less healthy foods, such as calorie-laden vending machine snacks and sodas. Tell employees to think ahead about what their meals will be at work, and offer the following suggestions:

  • Make fast food an occasional treat, not a daily meal;
  • Bring food from home; planning and packing a healthy meal in advance makes snacking and skipping meals less likely;
  • Plan a couple of quick, healthy meals rather than one large one. It's easier on digestive systems upset by the change in sleep/wake rhythms, and provides an opportunity for a couple of quick breaks away from work;
  • Avoid caffeine after the early part of the shift. While a little caffeine early on can help promote alertness, too much caffeine or caffeine taken close to the time the worker will be sleeping can further disrupt sleep.

[For more information, contact:

Kirsty Kerin, PhD, ergonomics specialist, Circadian Technologies Inc. Address: 2 Main St., Suite 310, Stoneham, MA 02180. Phone: (800) 284-5001. Web site:]