Fatigue Management in Night Shift Workers and Employer Risks

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5 September 2023

Fatigue Management in Night Shift Workers and Employer Risks

What did Three Mile Island, Chernobyl, and the Exxon Valdez accidents have in common? They all occurred during night shifts.

Night Shift is Here to Stay

Every night, 15 million Americans go to work. They will care for the sick, protect citizens from harm, bake bread, assemble machinery, fly planes, and complete hundreds of other necessary duties. They’ll return home as the rest of the world wakes and try to sleep while the sun shines.

People work the night shift for a variety of reasons:

  • Coordinating child care with other family members
  • Earning more with the shift differential pay
  • Allows for daytime activities such as school
  • Nights can be less hectic in the workplace
  • No open day shift positions
  • Rotating shifts are required by the employer

Night Shift Challenges

Adapting to the night shift is an enormous challenge for workers. All living things, including, humans, animals, and plants, have a natural 24-hour circadian rhythm that responds to light and dark. It directs the release of hormones, as well as regulating moods, level of alertness, and body temperature.

The circadian rhythm is controlled by a master body clock of sorts in the brain, situated near the optic (eye) nerve at the back of the brain. Depending on how much light the optic nerve detects, we feel awake or sleepy; with fading light or darkness, the brain detects night hours and produces the sleep hormone melatonin. When morning comes or when sunlight hits the back of the eye, we wake and become alert.

For night shift workers, there is a constant battle with their body clock. Trying to get quality sleep during the day can be nearly impossible because of the disrupted circadian rhythm. The result is often shift work sleep disorder, which the National Sleep Foundation extends to all shift workers, including night, rotating, and very early shifts. Symptoms of shift work sleep disorder can include:

  • Excessive daytime sleepiness when awake, with difficulty remaining alert and productive
  • Trouble sleeping, or insomnia, when trying to fall or stay asleep
  • Feeling tired and unrefreshed, even after sleeping
  • Difficulty concentrating
  • Irritability or depression

Night Shift Fatigue Health Dangers

Without proper rest of at least six hours during each 24-hour period, shift workers develop chronic sleep deprivation. Unable to catch up on sleep, the growing fatigue burden can lead to serious health, productivity, and safety consequences that can impact the company, especially if the worker is in a safety-sensitive position.

Long-term night shift workers are three times more likely than day shift colleagues to develop metabolic syndrome, a group of risk factors that increases the likelihood of serious medical conditions that can't always be seen without a medical evaluation, including:

  • Cardiovascular disease
  • Diabetes
  • Obesity
  • Depression and mood disorders
  • Ulcers and gastrointestinal problems
  • Problems with fertility and pregnancy
  • Cancer

Night Shift Fatigue Productivity and Accuracy Issues

Studies with nurses show that even moderate sleep deprivation can harm job performance, including operating equipment and driving, with the same effects as intoxication. Staying awake for long periods (18 hours or more) is comparable to a blood alcohol level of 0.08%, the legal level of intoxication in many jurisdictions. It’s enough to impair accuracy, hand-eye coordination, judgment, decision making, and memory.

Safety declines over successive night shifts, due to mounting fatigue. A report by Harvard University showed the risk increased to about 6% on the second night, 17% on the third, and 36% on the fourth night. As a result, night shift workers make five times as many mistakes as their day shift counterparts, and are 20% more likely to be involved in serious accidents.

Unable to resist the increasing tiredness, workers can actually fall asleep for 1-10 seconds. Completely involuntary, these microsleep episodes are dangerous, because while part of the brain remains alert, another area shuts down as the brain attempts to rest. Night shift workers are especially at risk for microsleep events that lead to car crashes as they drive home in the morning.

Night Shift Costs

How much does operating a night shift cost a company? Circadian, a large consulting company that specializes in shift operations, calculates an annual cost of $206 billion a year. This works out to $8,600 per worker.

Other findings by Circadian:

  • Because of lifestyle disruption, shift workers suffer a divorce rate of 60%.
  • The health-related issues mentioned above add another $29 billion a year.
  • Turnover can be as high as 300% for some industries, resulting in an extra $39 billion in costs.

Bloomberg.com cites legal fees of night shift accidents caused by lack of sleep. First, almost $6 million in damages when a Nabors Drilling Company employee fell asleep while driving home after his shift. Then, $52.4 million in damages was awarded to the family of a Conrail employee who was killed by a co-worker who admitted to coming to work after only 3-4 hours of sleep. Finally, a woman’s family was awarded $500,000 workers’ compensation after she was killed she fell asleep and her car drifted into oncoming traffic and was hit by a truck. She had been required to work six 12-hour shifts in a row at Namoi Cotton Co-operative. The court noted that “employment does not have to be the only, or even the main cause” of the accident. “It need only be a contributing factor.”

Lessons for Employers

Employers can not afford to ignore the challenges and risks of night shift work for their employees. These ten suggestions for improving conditions for night shift workers are a good place to start.

  1. Provide bright lighting during evenings and nights.
  2. Schedule no more than six consecutive 8-hour night shifts or four 12-hour night shifts.
  3. Shorter shifts should be set for hazardous or tiring job duties.
  4. Offer more rest breaks during the night.
  5. Discourage excessive overtime.
  6. Supervise and support new or inexperienced workers.
  7. Consider a policy that provides extra sick or vacation time for the night shift.
  8. Encourage workers to wear sunglasses on the way home in the morning to decrease the wake cycle phase of circadian rhythm.
  9. Provide education about how to improve sleep during the day and maintain a sleep schedule on days off.
  10. Train supervisors to watch for signs of fatigue and respond accordingly, including encouraging workers to see a physician if poor sleep is a chronic problem. A quick guide with more tips for employers is available at Business.com.

Employer Success Stories

  • When Unilever Group in Jefferson City, MO, increased shifts to 12 hours, but added longer breaks, productivity jumped 15% and accidents fell 40%.
  • Cellu Tissue Holdings strengthened safety training and gave night employees twice the number of permitted absences. Accidents dropped 50%, saving the company over half a million dollars a year.
  • Manitoba Hydro in Canada offers its workers free transportation home and back, eliminating the high risk of driving while fatigued.


Certainly, shift work is going to continue. However, employers need to recognize that 3 a.m. is not the same as 3 p.m. and that night shifts require a different strategy. With some extra attention, the company and its shift workers will succeed, staying healthy, safe, and productive.