Sometimes I get scared about falling asleep, as if something bad were to happen .

Maybe sleep with soothing music on. It might help.

Are you afraid of nightmares, perhaps?

Having chronic insomnia, I tend to be more afraid of not sleeping.

Unless you’re falling asleep while driving a car, no.

Have done

Yes.

I have to take antianxiety pills before bed, to deal with the fact that those with my particular terminal cardiopulmonary usually die in our sleep, I have woken up with too many nasty panic attacks if I don't take one. I also have to take another one when I wake up to help me get through my day.