Drowsy driving — Iowa Permit Test

Drowsy driving on the Iowa permit test — 4 rules, each with the reason behind it and a question on it while it is fresh.

The rules

Being awake for 18 hours straight is as impairing as a BAC of 0.08 percent, which is legally drunk.

Your body does not care why you are slow to react. A long day awake hurts your driving as much as drinking.

Being awake for 18 hours straight is as impairing as a blood alcohol concentration (BAC) of 0.08 percent, which is legally drunk and leaves you at equal risk for a crash.

Iowa Driver's License Manual, p.37

If you notice signs of drowsiness, take a break, pull over to a safe spot, or switch drivers.

Opening a window or turning up the radio does not cure being tired. Only rest or a fresh driver fixes it.

You should take a break, pull over to a safe spot, or switch drivers if you notice any of the following:

Iowa Driver's License Manual, p.37

Trouble remembering the last few miles you drove is a sign of drowsy driving.

If you cannot recall the last few miles, your brain was not really watching the road. That is your cue to stop.

Trouble remembering the last few miles driven.

Iowa Driver's License Manual, p.37

Drifting from your lane, tailgating, or hitting a shoulder rumble strip are signs of drowsy driving.

Your hands start to drift when your mind does. The rumble strip buzz is a warning to get off the road and rest.

Drifting from your lane, tailgating, or hitting a shoulder rumble strip.

Iowa Driver's License Manual, p.37

On the test

Being awake for how many hours straight is as impairing as a BAC of 0.08?

18 hours. Your body does not care why you are slow to react. A long day awake hurts your driving as much as drinking. Iowa Driver's License Manual, p.37: “Being awake for 18 hours straight is as impairing as a blood alcohol concentration (BAC) of 0.08 percent, which is legally drunk and leaves you at equal risk for a crash.”

How this works

Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.

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Learning one rule at a time, and proving it immediately, is what turns a manual you skimmed into something you actually know — and it makes studying feel like getting somewhere rather than like waiting to find out.

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Where these come from

Every rule here is checked against Iowa Driver's License Manual, published by the Iowa Department of Transportation, and against the state code itself. Last checked 2026-10-04.