My dog now sleeps in the kitchen at night and settles much better if we leave a light on for him.  Could he be frightened of the dark?

I think so , night lights work wonders.

Thanks, I thought I was going mad, and I think I got dogs and cats mixed up in the seeing in the dark thing... thats cats aint it.   So been today and got a night light for him. Up to now had to buy a baby play pen, a baby gate and a night light, I sometimes wonder if I got a pup or had a baby. ha ha

Yep its cats!

Yes it's possible - Bonnie doesn't like the dark either, and will stay in the garden (which is just as dark if not darker!) if there isn't a light on in the passageway where they sleep at night......