**Fatigue** in a driver can be caused by several factors related to their physical and mental state. Among these factors are:

- **Stress and worries**: These are internal factors that directly affect the driver's mental state, reducing their ability to concentrate and increasing irritability.

- **Excessive driving time**: Driving for long periods without rest can lead to fatigue, as the body and mind become tired, affecting reaction time and decision-making ability.

These factors are internal and personal, unlike external factors such as road conditions or weather, which are not the only causes of fatigue. Additionally, proper ventilation or a comfortable seat are not factors that cause fatigue, but they can help prevent it. Therefore, it is important to recognize and manage these internal factors to avoid fatigue while driving.