Late at night you realise you cannot remember the past several kilometres and your eyes keep closing. What is the only effective countermeasure?

Why C is correct

Fatigue is not a mood that can be distracted away; it is a state of the nervous system. The specific symptom described here — losing time, unable to recall the last stretch — indicates microsleeps are already happening, which means the driver has been asleep for seconds at a time while travelling at road speed. At that stage no stimulus reliably prevents the next one, and every folk remedy buys a few minutes in exchange for feeling safer, which is the genuinely dangerous part. The only intervention that restores function is sleep, and experience puts the worthwhile minimum at around twenty minutes.

Why the other options are wrong

A. Keep the interior light on and take a different route

Interior light and novelty of route remove nothing about the underlying state. Drivers who keep going generally recall noticing the change of route and nothing whatsoever of what followed it. Novelty occupies attention for perhaps a minute before microsleep returns, exactly as it does once anything stops demanding anything.

B. Turn the radio up and open the window

Radio and cold air lift arousal briefly before the microsleeps resume, frequently without the driver noticing they returned. They also produce confidence, which is worse than sleepiness.

D. Drink an energy drink and push on to the next stop

Caffeine takes time to act and does nothing about sleep already owed. Pushing to the next stop assumes the twenty kilometres in between survive it.

On the road

A driver losing time on the motorway drinks coffee at every service area, reaches home, and does not recall the last junction. The countermeasures worked right up to the point where they stopped working. Nothing else available inside a car does either, including everything sold as though it might. Twenty minutes parked somewhere safe is the difference.

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