**Fatigue** is a state that negatively affects the driver, and one of its main effects is that it **increases reaction time**. This means that the driver takes longer to respond to stimuli such as seeing a red traffic light or the need to brake in front of an obstacle.

- **Symptoms of fatigue** include difficulty concentrating, slower movements, and increased irritability. These symptoms contribute to the driver taking longer to react.

- **Reaction time** is the interval between perceiving a stimulus and responding to it. Under normal conditions, this time is from half a second to a second. However, fatigue prolongs this time, causing the driver to react more slowly.

- Other factors that also increase reaction time are sleep, advanced age, hearing or vision problems, and the consumption of alcohol or drugs.

In summary, fatigue not only affects the driver's ability to concentrate and make decisions but also **increases the time needed to react** to situations on the road, which can be dangerous.