Well I don't know if they are actually called head rests,
but I figured people would know what I'm talking about.
I don't "rest" my head on them normally,
but I do like to lean back and use it for posture sometimes
since I already like having the seat positioned upright, rather than reclined.
However, I have also attempted to use them to rest a passenger and this was a big mistake. It's a neck injury waiting to happen. With this kind of chair the only way to not get a neck injury by sleeping (as a passenger) for someone of my height is to either bring a thick pillow and wad it up, wear a neck brace or simply rip the dang thing off the back of the chair.
My biggest beef is that because when I drive I like to have the chair upright,
I now have to consciously lean my head forward,
so it does not touch the sloping "head rest",
which by merely touching it,
it seems to want to make my head tilt downward;
obviously bad when you want to look straight ahead,
so when I look straight ahead with this downward tilt,
it causes parts of my neck to pinch.