Mini-post: “Falling asleep whilst driving: are drivers aware of prior sleepiness?”

“Falling asleep whilst driving: are drivers aware of prior sleepiness?”

There’s newer work in this area and it’s a simulator study (which has limitations) but this was a nice study which, for me, drove home the importance and danger of sleepiness while driving (p1).

As you can see from the second image – tired driving predictably results in hazardous driving events – with higher subjective ratings of sleepiness more indicative of heightened minor & major events.

This study observed that “It was not possible for our subjects to fall asleep at the wheel and have an “accident” without experiencing a sustained period of increasing sleepiness, of which they were quite aware”.

All the events “happened after many minutes of self-reported sleepiness, and usually after a lengthy period of fighting sleep” (p1).

That is, while people are poor at predicting exactly *when* they’ll have a microsleep (I’ll post some research on this at a later point), microsleeps seem to be almost always preceded by obvious signs of subjective sleepiness.

Concerningly, “some subjects failed to appreciate that extreme sleepiness is accompanied by a high likelihood of falling asleep” (p1).

Thus, while we should try to avoid and minimise these situations to begin with (driving tired, driving during circadian low etc.), at the least, this study and later studies support the idea that we should listen to our bodies when it comes to obvious signs of sleepiness when driving.

Signs of sleepiness is a sign that you’re (probably) sleepy, and a sleepy head while driving is a dangerous head.