**Drowsiness** is a state in which the driver feels **tiredness, heaviness in the body, and sleepiness**. This state can occur long before the driver actually falls completely asleep.

- **Symptoms of drowsiness**: Before falling asleep, the driver may experience signs such as difficulty keeping their head upright, blurred vision, frequent yawning, loss of concentration, being easily distracted, restlessness or irritability, and difficulty remembering the last few kilometers driven. They may also drift out of their lane or fail to notice traffic signs.

- **Causes of drowsiness**: Sleeping fewer hours than usual, changing sleep hours, poor sleep, driving on roads with little traffic, consuming alcohol or medications, having sleep disorders, and driving at dawn or after eating can cause drowsiness.

Therefore, it is important to recognize these symptoms and causes to avoid accidents, as drowsiness affects the ability to drive long before falling asleep.