Every March and November, most people in the United States have to remember whether the clock is going to “spring” forward or “fall” back – and most importantly, whether they’ll get an extra hour of sleep or one less.
Talk of changing to permanent Daylight Saving Time (DST) has floated around for decades, but the House recently passed a bill proposing the time change, with President Donald Trump’s support.
Currently, Americans typically must move their clocks forward an hour in the spring for Daylight Saving Time, which “adds” an extra hour of daylight in the spring and summer evenings. Then, they go back an hour in the fall for Standard Time.
The Sunshine Protection Act would make DST year-round, shifting sunrise an hour later in the morning and sunset an hour later in the evening. One reason it cites is the potential to reduce traffic accidents nationwide, but that claim may not be as clear-cut as it seems.
Morgan, Collins, Yeast & Salyer is here to explain the impact permanent Daylight Saving Time could have on the safety of all the country’s road users.
The Threat Daylight Saving Time Poses to Safe Driving
Several factors associated with the change between Daylight Saving Time and Standard Time can affect driving safety. The two greatest impairments it may cause are decreased visibility and sleep disruption.
Decreased Visibility
When Americans “lose” an hour of daylight, more drivers are on the roads as it gets darker and darker each week.
Nighttime driving poses a significant risk to road users, with the Federal Highway Administration (FHWA) reporting that around half of all traffic fatalities – and over three-quarters of pedestrian fatalities – occur at night, even though only about a quarter of travel happens after dark. The agency attributes the inherent challenge of driving at night to the reduced visibility.
According to a research review published in Ophthalmic and Physiological Optics (OPO), evidence suggests that nighttime lighting conditions reduce visual function. Those effects worsen with age and existing visual impairment. The research also points to bright lights and blinding glare from LED streetlights and vehicle headlights, which contribute to dangerous conditions.
Sleep Disruption
People experience jet lag when flying across different time zones for a reason. The body functions on an internal clock, and sudden time changes can disrupt natural sleep rhythm.
Research suggests that the transition to DST is similar, as it negatively impacts both sleep duration and quality, leading to increased sleepiness. The National Sleep Foundation (NSF) considers drowsy driving a common form of impaired driving, grouped with drunk, drugged, and distracted driving. The risk is often underestimated, but studies show that drowsiness is a factor in up to 21% of all traffic collisions resulting in death.
What the Data Says About Time Change and Crash Rates
A recent study published in the Journal of Safety Research, supported by the Insurance Institute for Highway Safety (IIHS), analyzed data to illustrate how the switch between Daylight Saving and Standard Time affects traffic safety.
The researchers used the NHTSA’s Fatality Analysis Reporting System (FARS) to investigate how many fatal collisions happen in the country in the 5 weeks before and after these biannual time changes. They focused on crashes that happened when light conditions changed in all states in the contiguous U.S. that practice DST, from 2010 to 2019.
Here’s what the research showed:
| Fatal crashes for vehicle occupants | Fatal crashes for pedestrians and bicyclists | |
| 5 weeks after change to Standard Time | –7.1% | +13% |
| 5 weeks after change to Daylight Saving Time | +12% | -24% |
Source: https://www.sciencedirect.com/science/article/abs/pii/S0022437525000076
Overall, there was a net decrease of 26 fatal collisions for pedestrians and cyclists across both time periods – all of which could be attributed to changing light conditions. While vehicle occupants saw a net increase of 29 fatal crashes, only 2 of those additional crashes were linked to the light changes.
The numbers show that switching between DST and Standard Time has opposite effects on vehicle occupants and pedestrians. That distinction is especially evident when it comes to the lighting at the time of the accident.
The Potential Impact of a Permanent Time Change on Road Users
The impact of making Daylight Saving Time permanent will depend on many factors, particularly the type of road user. Some supporters of making the change permanent discuss the potential decrease in motor vehicle collisions nationwide. But the data reveals that the claim might not hold true for drivers.
Still, vulnerable road users like pedestrians and bicyclists would likely be much safer on the streets with a permanent switch to DST. While DST causes a later sunrise for groggy commuters, Standard Time often leaves the evening rush hours pitch dark after an early sunset – the most dangerous time for vulnerable road users.
For 2024, the IIHS reports that 73% of all pedestrian deaths happened between 6 p.m. and 6 a.m., with 24% just from 6 p.m. to 9 p.m. With an extra hour of daylight during the busy commute home, pedestrians and cyclists would likely face less risk.
Unfortunately, there does not seem to be a simple solution that will make the roads safer for everyone during both the early morning and late evening hours. Everyone can work together to reach their destinations safely, regardless of lighting conditions, though.
IIHS President David Harkey says the study highlights how visibility is crucial for preventing pedestrian and bicyclist fatalities. His suggestions include “better lighting, especially at crosswalks, improved headlights, and reflective or light-colored clothing.”
Legal Responsibility for Car Accidents Caused by Light Conditions
Drivers have a duty to drive safely, no matter how dark it is after the time changes. When a driver causes a car accident because they failed to adjust their behavior to the lighting conditions, the victims can hold them liable for the resulting losses.
However, a pedestrian or bicyclist who darted into the dark road outside a crosswalk could also bear some responsibility for a collision.
Because liability after a car accident will depend on the specific facts of each case, it’s best to check with an experienced personal injury lawyer.
