What are serious signs of drowsiness while driving?

Having trouble keeping your head up and drifting between lanes are serious signs of drowsiness while driving. These behaviors indicate the driver is not fully alert or attentive, which significantly increases the risk of a crash. When a driver struggles to maintain head control, it often signifies that they are experiencing fatigue or sleepiness. Drifting between lanes can also mean that the driver is unable to stay focused on the road, which is a critical requirement for safe driving.

In contrast, feeling relaxed and calm might not necessarily suggest drowsiness; instead, it could indicate a normal state of comfort during driving. Listening to music or driving with the windows down are typically activities that many drivers engage in to remain alert, rather than indicators of drowsiness. These options do not reflect the same level of engagement or awareness required for safe driving as the signs of struggling to keep head control and lane positioning do.