Blog /

The Most Dangerous Time of Day for Driving May Surprise You

Fatigued woman behind the wheel of a car

For many people, driving is a daily part of life. And because we’re behind the wheel so often, it’s easy to get complacent and forget that driving is a huge responsibility—the driver holds in his or her hands the lives of their passengers and of others on the road. 

No matter how experienced or well-trained a driver is, operating a vehicle at high speeds never ceases to be a hazard. And there are times when this hazard is elevated. For example, even though most of us see the evening rush hour as a long and unpleasant journey home, according to the Insurance Institute for Highway Safety most car crashes happen between 3 p.m. and 9 p.m.

Circadian rhythm

So why does the road that people take every single day suddenly become more dangerous in the late afternoon? It’s not only the number of drivers on that road that affects safety, but it’s also the combined influence of complacency and human circadian rhythm causing fatigue.

Everyone experiences natural changes in sleepiness and alertness throughout the day. These are controlled by our circadian rhythm, which is closely linked to each person’s biological clock. It responds to light and dark, and it affects our physical and mental states. It’s natural to feel a dip in energy levels in the afternoon, but it can lead to a lack of focus that is exacerbated by sleep deprivation and other human factors. 


Regularly not getting enough sleep is not only detrimental to a person’s overall health but also to their safety because it causes or contributes to fatigue. And fatigue can be deadly because it reduces concentration and reaction times. It’s also worth noting that fatigue affects the ability to control emotions (how often have you witnessed someone snapping at others when they’re tired?), which can be dangerous if unchecked on the road. Fatigue may also alter how we perceive and respond to risk. 

The regular dip in energy people experience in the afternoon, sometimes paired with fatigue and, more often than not, with complacency, can lead to many small errors, most of which might only cause some lost time or irritation. But some mistakes, even very small ones, can cost people their lives, especially when driving. So it’s important for EHS professionals to address the subject of fatigue and complacency behind the wheel because when someone is traveling down a well-known street while tired at the end of their work day, their chances of being in a car crash go up. 

It’s not always easy to address biological and mental barriers to safety, but there are steps that can be taken to educate workers on how to mitigate the effects of being tired. Learning more about fatigue and one’s own circadian rhythm can help prevent making dangerous errors at the wrong times. 

There are also resources for employers to help their workers address fatigue and complacency. It’s in everyone’s best interest to keep safety top of mind whether they’re at work, at home or on the road—and that means staying alert to the dangers of fatigue. 

Guide to Distracted Driving Prevention

Cut Down on Driver Error

Learn how to drive distraction away and get drivers to keep their eyes (and mind) on the road.

Get the free guide now

Tagged , , , , ,