How Do You Prove a Driver Was Drowsy in an Illinois Car Accident Case?

 Posted on September 08, 2025 in Car accidents

If you were involved in a car accident that was caused by a driver who fell asleep at the wheel, it is natural to want that driver to pay for your medical bills and lost income. However, it is not typically an easy task to prove that another driver was tired and that this caused your accident. Challenging as it may be, proving driver fatigue is possible with strong evidence. For help understanding how, contact a Des Plaines, IL personal injury lawyer.

How Can You Prove That a Tired Driver Caused a Crash?

Unlike intoxication, which can be confirmed with a breath test, drowsiness is not something that can be proved by any specific test. Most drivers will not admit that they fell asleep at the wheel or were too tired to drive safely. That means accident victims and their attorneys typically need to gather multiple forms of evidence to show that fatigue played a role in the crash.

Attorneys use several types of evidence to argue that fatigue caused or contributed to an accident:

• Witness Testimony: Passengers or bystanders who noticed yawning, drifting between lanes, or the driver nodding off

• Timing and Circumstances: Accidents happening in the early morning, late at night, or involving a car veering off the road

• Electronic Evidence: Toll pass data, cell phone usage, and surveillance footage

• Medical Records and Prescriptions: Certain conditions like sleep apnea or medications with drowsiness warnings

• Police Reports: Signs of drowsiness, such as bloodshot eyes, confused speech, or an admission of being tired, noted by officers at the scene of a crash

How Does Comparative Fault Impact Drowsy Driver Crash Cases?

Under 735 ILCS 5/2-1116, Illinois follows a modified comparative negligence rule. This means the court will consider whether both drivers share blame for the crash. For example, if a drowsy driver caused the accident but you were also speeding, you could be found partially responsible for the accident and your compensation would be reduced by your percentage of fault. If you can gather strong evidence demonstrating that the other driver was fatigued, it may help you minimize the amount of blame shifted onto you.

Because drowsy driving can be difficult to prove, insurers often dispute these claims. They may argue that something else caused the accident or that your injuries are not as severe as you claim. A skilled attorney can put a case together by working with accident reconstruction experts, and push back against attempts by the other driver’s lawyer or insurance company to claim you caused the accident and are not eligible for damages. 

Contact a Des Plaines, IL Drowsy Driver Accident Lawyer

Recovering from a crash is hard enough without having to battle insurers over whether the other driver’s fatigue caused the collision. At Quinn Law Group, LLC, our team is dedicated to pursuing fair compensation for medical costs, lost wages, and other damages while our clients focus on recovering. For personalized legal guidance, call the Park Ridge, IL personal injury attorney at 847-232-7180 today to set up a free consultation.