Re: falling asleep all the time
I strongly recommend you get him to see a sleep specialist.. this could be severe sleep deprivation due to hypopnea or obstructive sleep apnea.. or as the other poster mentioned narcolepsy. I am leaning more toward the hypopnea or sleep apnea.. 1) because they are more common.. 2) because these sleeping events happen when he gets still.
In the case of Narcolepsy.. they would happen at anytime. Walking down the street.. standing in line... you just shut down.. your husband is doing this when he is sedentary.
In either case this is serious.. what if he does it driving? He is a danger to himself and others if this occurs.
If we learn by our mistakes, I am working on one hell of an education.