I think with this one the 'Sleep Advisory Service' and http://clivewhite.co.uk/?p=19143 are pretty similar. This is what they said:

'Freefall position - Those people who lie on their bellies with arms under or wrapped around a pillow with head turned to the side, make up 7% of the population studied. Freefallers are brash, outgoing, and are very uncomfortable with criticism.'

I often sleep like this - but I have an excuse!

After my bike accident 20 years ago I have a bad leg and a foot that is constantly painful, this means that I frequently hang it out the end of the bed as that is the least painful way for it to be. This all despite my wonderful Hugs Mattress :D.

I will explain about my accident in another post and will accept no criticism of my decision...