The **reaction time** is the interval that elapses from when a driver perceives a stimulus, such as a red traffic light, until they respond, for example, by pressing the brake. Under normal conditions, this time is usually between half a second and one second.

However, the reaction time can **increase** due to several factors related to the driver's **physical and psychological state**. Some of these factors include:

- **Fatigue** or tiredness.
- **Drowsiness**, which not only lengthens the reaction time but also makes decision-making difficult and can lead to briefly falling asleep at the wheel.
- **Advanced age**, which can affect reflexes.
- **Hearing or vision** problems.
- **Illnesses** or the consumption of certain **medications**.
- Consumption of **alcohol** or **drugs**.
- Having **overeaten** before driving.
- **Excessive heat** inside the vehicle.
- An **altered mood** or lack of attention.

Therefore, the reaction time is not fixed and can vary significantly depending on the driver's physical and mental state, as well as environmental conditions.