If you drive a particular journey often enough, it begins to feel like the distance has increased. Having the radio on, or music can help, as can sharing the journey with a companion. You can chat or play games such as I-spy or, as we often do, alphagames. However, even then, you will often find there are times when there is simply nothing to say and you just don't feel like playing any games. You're on a motorway, doing a steady 65mph, you and your companion have exhausted all the normal topics of conversation.
And you begin to zone out.
It's not the same as falling asleep, but it can be just as dangerous.
If I am on my own and I feel like I am slipping into The Zone, I make sure I have some upbeat music - rock, ska, pop, whatever - and crank up the volume to disguise my abysmal singing voice. If Julie is with me, then I try and come up with a speculative area for a conversation. Why? Because there is no way any answer my wife would come up with would be in any way dull. In fact, I will often be in danger of not being able to see because of laughing so hard...
On one journey, I felt my eyes unfocusing. Time to come up with a conversation starter. Hm. How about reincarnation?
Trust me when I say that the car was quiet for a little while following that - although that was mainly because I honestly couldn't think of anything to say...
This seems apt enough, though.