Commercial drivers know that cell phones, food, and even the radio and GPS can be dangerous distractions when they’re behind the wheel. But are your fleet drivers aware that their emotions can also serve as a hazardous distraction?

In fact, a recent large-scale study of 1,600 crash events over a 3-year period found that drivers who are observably angry, sad, or agitated increase their risk of getting into an accident by nearly tenfold. The findings were reported in Proceedings of the National Academy of Science.

Moreover, negative emotions such as anger and sadness have a physical effect on the body — shrinking one’s field of vision. So drivers who are upset actually see less of the road, which dramatically increases the odds of an accident.

Take the time to remind your drivers that it’s in their best interest to keep their cool when behind the wheel. Experts offer the following advice:

• If you’re feeling distressed or mad, take some time to cool down before you jump into the car.

• Never engage with hostile or aggressive drivers — this can only fuel your own impatience or anger.

• If you find yourself angry or sad while behind the wheel, pull over and take some long, deep breaths.

• Wait to calm down before you get back on the road.

• Stay focused by shifting your attention from your own state of mind to the state of the road.