Which of the following is an effect of drowsy driving?

The effect of drowsy driving is evident in several ways, but the ability to recall the last few miles traveled can be significantly impaired. When someone is drowsy, their brain's processing capability diminishes, leading to lapses in memory and attention. This can result in a person driving for a stretch without being fully aware of their surroundings or the actions they've taken.

Drowsiness reduces cognitive functions critical for safe driving, such as alertness and attention span. It can lead to microsleeps—brief moments of sleep that can occur without the driver even realizing it. Because of this, recognizing that one cannot remember the last few miles is a warning sign of the severe effects that drowsy driving can have.

While increased reaction time is also a consequence of drowsy driving, the inability to recall recent driving can be a more overt and alarming indicator of the risks involved. Feeling overly energetic and improved concentration are not effects associated with drowsy driving, as they do not align with the physiological and psychological impairments that arise in such situations.