I don't know if I can live with such guilt I might become suicidal. He is probably kicking his butt every day and how stupid it was to lose his family just because he fell asleep. I really feel sorry for him.
Probably its in the way you drive. I know that I can never fall asleep while driving because I drive a manual car. Also it is recommended that you take a different route where possible to get to home regularly, so that the trip home does not become monotonous.
Once a friend and I were driving in England and we both had a high temperature but had to be about some business. He tried to stay awake but at some point we BOTH were out and cross four lanes of a dual carriage way (highway) not knowing what happened. I won't go into miracles here.
AAA: Drowsy driving plays larger role in accidents than federal statistics suggest. AAA Foundation for Traffic Safety studied 700 accidents and found that drivers were drowsy in 9.5%, much more than federal statistics suggested. Source 8i.