Unfortunately,all I can advise is that see his GP,and asked to referred to a sleep disorder clinic.
Yes,there are such things!
He would have to go in for one night,maybe once a week for a few weeks,and they would wire him up to a computer and study his sleep pattersn.
They would also film him while he sleeps (or not) and put the two together to try and find the problem.
It might (although I am NOT medical) be either of these two thing:~
Sleep Apnoea
http://en.wikipedia.org/wiki/Sleep_apnea
or a form of Narcolepsy
http://en.wikipedia.org/wiki/Narcolepsy
but of course there are probabl quite a few more things that may be causing it.
Please,DO try and get it him to the GP,it's not something he (or you) can cure on your own, from the sound of it.