**Drowsiness** negatively affects driving ability. When a driver is drowsy, their **movements become slower and less precise**. This is due to several factors:

- **Slower reaction**: Under the effects of sleep, the driver's reaction time increases, meaning it takes longer to respond to situations on the road.
- **Difficulty performing movements**: Drowsiness causes a feeling of heaviness in the body, making movements slower and less coordinated.
- **Concentration problems**: Lack of attention and distraction are common, affecting the ability to make quick and precise decisions.

These combined effects make driving under drowsiness dangerous, as the driver cannot adequately react to changing traffic conditions. Therefore, it is crucial to recognize the symptoms of drowsiness and stop to rest if necessary.