Researched and Compiled

by Tony Rieck

T.R. Consulting, Inc.

January 2002







Today, many employees are subjected to extended workdays and extended workweeks.  Some employers are adopting 4 day work weeks with 10 hour shifts due to perceived advantages to both the employer and the employee.  Other employees work extensive overtime hours either out of need or due to a desire to advance.  The result, for many workers, is fatigue and fatigue can cause a decline in safety and alertness, especially for those working 12 hours or more.  In 1993, the National Commission on Sleep Disorders Research estimated that over 70 million U.S. workers are overly tired.  The estimated cost of accidents where workers could not remain alert or awake ranged from $50 billion to over $100 billion annually when accidents, medical costs and absenteeism were considered.


The stories abound.  When potential exposure includes heavy equipment or handling of hazardous materials, the risks posed by fatigue multiply.  The Exxon Valdez, Chernobyl and Three Mile Island accidents have all been linked, in part, to worker fatigue.  Those working around heavy equipment or operating heavy equipment are vulnerable to the effects of fatigue as well.  In one incident, a worker dozed off in a crane cab during a break while working the third of three consecutive 13 hour shifts.  When he awoke, he exited from the wrong side of the cab and fell 35 feet to his death.






Historically, humans have lived by day and slept by night.  To maintain good health and avoid the deleterious effects of sleep deprivation, it is commonly accepted that people need between 6 and 8 hours of continuous sleep each day.  While there are individual variations, less than 5 hours of sleep in a day is known to cause forgetfulness and continual patterns of sleep consisting of either less than 5 hours or more than 9 hours is associated with early mortality.  When a person does not get enough rest and appropriate sleep, not only can fatigue set in, but the cumulative effect can result in serious sleep deprivation.  Sleep deprivation can cause the body to call upon its energy reserves and leads to a “sleep debt”.  The consistent conclusion of studies has been that sleep deprivation results in loss of concentration, forgetfulness, inattentiveness, reduced cognitive ability, increased reaction time and diminished alertness.  When an individual’s level of alertness decreases, the individual is no longer as capable of making good decisions, performing tasks or responding quickly to unusual or emergency situations.  Estimates provided by the National Transportation Safety Board stated that as many as 40 percent of heavy truck accidents involved fatigue where drivers had approximately 5.5 hours of sleep in the period preceding the accident.  It is easy to see that fatigue is an important factor in workplace safety.






Lawyers have become increasingly aware of fatigue and the ramifications not only to employees directly, but also to the public at large.  In Missouri, an appeals court held that the claims by a brakeman that inadequate sleeping facilities provided by his employer constituted unsafe working conditions.  His claims that sleep deprivation had caused his heart disease and gastritis were allowed.  In another lawsuit, a third party injured in a car accident sued the employer of the driver deemed at fault.  That driver had worked three shifts in a 24 hour period and the court declared that an unreasonable and foreseeable risk of harm was created through the employer’s conduct.  The plaintiff was awarded $400,000 in damages by the court.






Micro-sleep and automatic behavior syndrome are two behaviors associated with fatigue.  A fatigued individual is more susceptible to these behaviors that are known to create dangerous situations and contribute to accidents and injuries.  A micro-sleep is a brief nap that lasts from a few seconds to a few minutes.  Micro-sleep is most common when an individual is fatigued or bored.  Micro-sleep is a primary suspect in many vehicular accidents.  Automatic behavior syndrome is much like micro-sleep except the eyes remain open and the individual continues performing routine tasks.  A driver traveling down the expressway to a routine destination passes his exit.  A vague picture of the traffic remains in the driver’s memory, but there is no recollection of having seen the exit.  Such a scene could be termed automatic behavior syndrome.  Driving is used here as an example as most workers must drive commuting to and from work and/or from the workplace to the worksite.






Some important findings from studies:


*        Surveys indicate that 30% of motorists have experienced micro-sleeps behind the wheel and that as many as 80% of  those working around the clock had micro-sleep episodes.

*        A survey of 882 workers in 1994 found that sleep disorders were a primary cause of  workplace accidents.  55% of those polled who said that they problems sleeping or staying awake were involved in 75% of the accidents that required medical treatment.

*        Those sleeping during the day are estimated to sleep 1.5 – 2 hours less than night sleepers on average.






Contributors to fatigue include stress, worry, sleep apnea, insomnia, lack of exercise, improper diet and insufficient sleep.  While the symptoms of fatigue can vary by individual and by the degree of fatigue, the generally accepted symptoms of fatigue are:


*        Sleepiness

*        Depression

*        Irritability

*        Headache

*        Reduced cognitive ability

*        Reduction in alertness

*        Memory and concentration lapses

*        Giddiness

*        Loss of appetite

*        Digestive problems

*        Decreased resistance to illness





You can get additional information on fatigue from NIOSH.  Call NIOSH at (800) 35NIOSH and request their booklet, “Plain Language About Shiftwork”.