Your husband may be getting narcoleptic:
Narcolepsy is a sleep disorder that causes overwhelming and severe daytime sleepiness. Pathologic sleepiness is characterized by the fact that it occurs at inappropriate times and places. The daytime sleep attacks may occur with or without warning, and can occur repeatedly in a single day.
I had sleep apnea for years until I got a CPap machine last December.
I was having alot of trouble not sleeping at night and having uncontrollable episodes of sleep while at work.
As a medical assistant I was taking a lady's blood pressure one day and dozed right off. It can be scary and dangerous too. I have driven in my car like that when it was all I could do to stay awake.
You all might want to think about a sleep study.