Was just at a water park with my family and the guards there were doing this constant head nodding. Kind of disturbing to watch if you are not expecting it. But I looked it up and the explanation is they are "scanning" - making sure to move around their heads to observe their area better and not rely on just the peripheral vision.

Owls do that as well. Even I do it when getting to an intersection somewhat. I lean into the steering wheel and bob my head up and down a few times. I imagine it might look pretty ridiculous to someone from the side.

Driving is probably one of the most dangerous things we do here in US. Anything to make it safer is a good thing.

One of the tricks I learned from driver's ed in back in Eastern Europe is if you drive at night, and incoming traffic is blinding you, don't stare directly into the beam, but turn your head slightly to the right, such that you'd still see ahead but it would be out of the corner of your eye. Obviously not ideal as you're using your peripheral vision but if the alternative is to blinded and not see anything at all, it is still better. I've used that trick enough times since then and it seems to work pretty well.