Working shifts can result in significant fatigue, making the risks of driving greater.  For example, over 40% of shift workers report having nodded off while driving to or from work; 24% report that this happens several times per month.  And, 60% of shift workers report feeling drowsy at work several times per month; 11.6% report feeling this way several times per shift.  More than 25% of shift workers report making mistakes of inattention several times per month. [1]

The U.S. National Highway Traffic Safety Administration (NHTSA) estimates that approximately 100,000 police-reported crashes annually involve drowsiness or fatigue as a principal cause (about 1.5 % of all crashes).  A conservative estimate of fatigue related fatalities is 1,500 per year or 4 % of all traffic crash fatalities. At least 71,000 people are injured in fall-asleep crashes each year. NHTSA estimates that these crashes represent $12.5 billion in losses each year.

Impact on Shift Workers

The National Transportation Safety Board (NTSB) estimates that 31 % of commercial driver deaths are fatigue related.  Most shift workers don’t get enough sleep.  They sleep an average 6.5 hours on workdays; workers who only work the nightshift sleep even less.  The underlying causes of driver fatigue appear to include driving during early morning hours, working long shifts, and driving after having worked a series of night shifts.  The most dangerous hours for sleep-related accidents are between midnight and 7:00 am, and 2:00 pm and 5:00 pm.

In a study of 35,217 current employees or recent retirees of the French National Electricity and Gas Company, released in April 2006, 1.3 % of all participants reported at least one accident associated with being sleepy over the preceding three years.   Near-miss accidents associated with sleepiness were reported by 18.3 % of the participants (10.6 % with one sleepy near-miss, 5.9 % with two-to-three sleepy near misses and 1.8 % with four or more sleepy near-misses).   This study indicates that near-miss sleepy accidents are common and dangerous. Near-miss sleepy accidents occur in 14 times more people than actual sleepy accidents, and the near-misses appear to predict who is at risk for any type of actual accident. [2]

The study found a significant connection between self assessed driving while sleepy and the risk of serious road traffic accidents in the next three years.  The risk increased even more with reported frequency of driving while sleepy.  When the analysis was restricted to the subsample of participants who did not report any sleep disorders, the association was even stronger; self assessed drowsy drivers without sleep disorders had the greatest risk of traffic accidents. 

Ways to Prevent Drowsy Driving

There are some warning signs to pay attention to while driving:

• Yawning and not being able to keep your eyes open.
• Forgetting the last few minutes you’ve driven.
• Your car starts drifting out of your lane.
• You can’t concentrate and your thoughts start wandering.

To prevent being susceptible to drowsy driving: 

• Get enough sleep.  Adults should get seven-to-eight hours of sleep each night.
• Take breaks while driving.  If you are drowsy while driving, pull off to a rest area and take a short nap, preferably 15-20 minutes in length.
• Consume caffeine.  Caffeine improves alertness in people who are fatigued; but don’t drink it too close to the time you are going to go to sleep.
• Do not drink alcohol.  Alcohol can further impair a person's ability to stay awake and make good decisions.
• Do not drive late at night unless well rested. 
• Do not drive alone; drive with a partner.
• If you think you might have a sleep disorder, see your primary care physician.

[1] Circadian Technologies, Inc. Health in Extended Hours Operations: Understanding the Challenges, Implementing the Solutions, copyright 2003