Of those that habitually drive on the right side of the road so are seated on the left, the side they sleep on is:

Mathyj = left
Rrumbler = left
ted dehaan = left
rspears = right
Henry Rifle = left
34_40 = left
lurker mick = closest to the bathroom.

So that's five out of seven who sleep on the left; a majority.

Of those that habitually drive on the left side of the road so are seated on the right, the side they sleep on is:

me = right
bathcollector = right
Moose = centre (He's single - never been married.)
sharpmark = right
Goose = furthest from the door, but when alone = left (He's a mystery that boy, he works for the Diplomatic Corps; China one month, France next month, Mexico the month after, then on to London...)

So that's three out of five who sleep on the right. Once again a majority.

Conclusions?
I'm buggered if I know!
Draw your own!

But it would appear that my drunken acquaintance's comments may have a germ of truth in them.