**Sleep disturbances** can significantly affect the driver's condition. When a person experiences **drowsiness**, they are in a state of **fatigue** and **heaviness** in the body, which can lead to a series of symptoms that affect the ability to drive safely.

- **Symptoms of drowsiness** include difficulty keeping the head upright, blurred vision, frequent yawning, and loss of concentration. These symptoms can make the driver feel **restless or irritable**, which can translate into **nervousness and aggression** at the wheel.

- Additionally, drowsiness can cause the driver to be easily distracted, not pay attention to traffic signs, and drive too close to the vehicle in front, increasing the risk of accidents.

Therefore, it is crucial to recognize these symptoms and take measures to avoid driving in a state of drowsiness, as it can compromise road safety.