I've known for some years that driving a car while perceptibly under the influence of any alcohol at all is a terrifying experience. Once, due to bad organisation, I drove after drinking half a pint of Guinness (which ought to have put me a comfortably long way within the legal limit), and that was so scary I decided never to do anything like it again.

Since then I've discovered that a number of other things involving drinking and cars make me scared in much the same way.

For example, a couple of months ago, I was sitting in the pub with some friends, and the conversation turned to the fine points of road safety, and what drivers and cyclists should do in particular situations. After a few minutes I found that I needed to go and find some people who were talking about something else, because being perceptibly drunk and even imagining myself at the wheel of a car brought on much the same sort of fear.

It gets sillier. Being in a car driven by somebody else while I'm drunk can also, I've found, make me somewhat anxious. I think this one is because, having my own car, I'm very rarely driven by somebody else at all. So usually if I'm in a car I'm also in the driving seat. Hence, my subconscious must have felt, if I'm in a car and I'm drunk then I'm probably doing something dangerous.

The thing that brings this to mind today is that yesterday evening I went to the pub, and then walked home and went to bed. I fell asleep, and had a dream involving driving a car. Somehow, in the dream, I was drunk, which turned the dream into a nightmare. I don't know whether being drunk in the dream had anything to do with being drunk when I went to bed, but I suspect it probably did; in which case, even drunkenly dreaming about driving appears to be unacceptable to me.

I suppose it's comforting to know that I have such good defences against accidentally doing anything stupid of this kind in real life. But it would be nice if those defences didn't keep firing for the wrong reasons…