Studys have shown it's actually worse than drink driving and it's illegal without a hands free kit over here. I agree with Shaggy, though, they're solving the wrong problem.

All I can say to that is it's easy to sleep with a gun under my pillow.
I have an occasional tendancy to walk, talk, shout and once even destroy a built in wardrobe in my sleep. Putting a gun under my pillow probably wouldn't be the best idea. I think you raise a good point though, it's about cost/benefit. For you, although the benefit is small (in terms of the probability of actually needing to use it rather than any sense of security), so is the cost. For Shaggy the benefit is equally small but the cost is much greater. I think that's another difference between the US and UK though. Over here having a gun is a big deal; over there it's like having, well, lunch.