I'm sorry - your friend needs to be more vigilant about insisting that he have a sleep study. It' snot just about her misery - which I understand is significant. Her husband is not going into REM sleep and is severely sleep deprived. His body is not going into that stage where it repairs and heals itself. He needs to be evaluated for sleep apnea. This is not just an inconvenience - he is quite possibly a danger to himself or others.
She should sleep in another room so that she is rested enough to be save driving. He is not safe behind the wheel, and she should refuse to drive with him or allow him to drive the children, even if he says "I'm fine." There are other health risks for untreated sleep apnea as well, and they are not minor.
They should not be deterred by stories about sleep apnea equipment (CPAP machines and so on). There are new treatments, both in terms of a simple breathing apparatus and also outpatient medical treatments that improve the shape of the soft palate and other structures in the back of the throat. For many people, these take care of the problem.
If she refuses to drive with him and insists that he increase his life insurance, maybe he will get the message. Our family has been positively impacted, and our marriage enhanced, by seeking treatment.