What can happen if you ignore signs of tiredness?

You answered correctly. Ignoring signs of tiredness while driving is very dangerous because it can cause microsleep, a brief and uncontrollable episode of sleep, even if your eyes are open. It also leads to a lack of concentration, which means you might not notice important things on the road. Both of these significantly increase the chance of making driving mistakes, such as braking too late or steering incorrectly. In Germany, drivers are required to stop and rest if they become tired, because fatigue can be just as risky as driving under the influence. Always take breaks if you feel sleepy to keep yourself and others safe.