Author Ellen Szubski
Every spring, the United States shifts the clocks forward one hour creating an extra hour of light in the evenings. However, this shift may be linked to a slight increase in fatal traffic accidents immediately following the time change. It is theorized that the increase in fatal traffic accidents is due to two things: people losing an hour of sleep and the low illumination conditions of morning commuters.
Every spring, people set their clocks forward one hour for daylight savings time.
“Springing forward” typically leads to people losing an hour of sleep. Driving while fatigued can have a significant impact on car driving performance, leading to impaired cognitive and physical abilities that increase the risk of accidents. Fatigue can affect a driver’s motor coordination and physical abilities, such as steering control and maintaining a steady speed, which are essential for safe driving. It can also slow down a driver’s reaction time therefore making it more difficult to promptly and appropriately respond to unexpected driving events such as sudden braking or swerving vehicles.
Fatigue can also impair cognitive functions, including decision-making abilities. Impaired cognitive functions can lead tired drivers to make poor judgments or risky decisions on the road. Difficulties in maintaining concentration over long periods can also stem from fatigue, increasing the likelihood of lapses in attention and awareness while driving. Fatigue can result in reduced alertness and vigilance, making it harder for drivers to stay focused on the road. In extreme cases of fatigue, drivers may experience brief episodes of involuntary sleep known as microsleeps, lasting from a fraction of a second to several seconds. During microsleeps, drivers are effectively asleep and unaware of their surroundings, posing a severe danger on the road.
Overall, fatigue significantly impairs driving performance and increases the risk of accidents. It is essential for drivers to recognize the signs of fatigue, such as yawning, heavy eyelids, and difficulty focusing, and take the appropriate measures to prevent driving while tired, such as taking breaks, getting adequate rest, and avoiding driving during times when they would typically be asleep.
In addition to drivers losing an hour of sleep, the illumination of morning commuter’s driving environment decreases with the spring daylight savings transition. The human visual system functions on visual information in the form of light. This light stimulates the cones and rods within the retina in our eyes so that the visual information can be converted into electrical impulses that are then sent to our brain to produce the image. Due to the capabilities and limitations of the human visual system, our vision is severely limited in low luminance environments. Both the visual ability to recognize objects and see fine detail, and the ability to recognize low contrast objects/unlit objects are diminished in low luminance environments. During the spring daylight savings transition, morning commuters go from driving in a higher luminance environment to a lower luminance environment as our clocks “spring-forward.” This shift in luminance may be linked to the increase in fatal traffic accidents reported immediately after the spring daylight savings transition.
So, while daylight savings provides an extra hour of daylight in the evenings, drivers should be aware of the increased risk of traffic accidents immediately following the spring shift towards daylight savings time and take precautions.
Ellen Szubski, Ph.D., CXLT, CPSI, AHFP, is a human factors consultant at The Warren Group. She earned a Doctorate of Philosophy in Human Factors Psychology and a Master of Science in Applied Psychology from Clemson University. She did her dissertation on “The Influence of Pedestrian Biological Motion on Time-To-Collision Estimates at Night”. She is also a Certified XL Tribometrist, Certified Playground Safety Inspector and a Certified Associate Human Factors Professional (AHFP). Prior to entering the forensic field, Ellen planned and conducted experiments for a major bicycle manufacturer. She also conducted laser strike perception studies for the Department of Defense. Ellen applies her experience in Human Factors to the analysis of crash investigations and other personal injury matters. These matters often include collisions involving vulnerable road users and drivers, driver distraction, and slips, trips, and falls. She utilizes her knowledge of OSHA regulations, codes, and standards in her analysis of premises liability incidents and safety consulting. Ellen is a current member of the Human Factors and Ergonomics Society (HFES) and it’s Forensic Professional Technical Group.
