He needs a sleep study soon or he might not wake up at all. A sleep study might aid in diagnosis and just tell him all he has to do it sleep. He will be attached to some equipment to monitor his breathing , oxygen
in his blood etc., I had one done, I had no complaints, but you husband needs to see someone to diagnose this problem because it is going to adversely affect his health more and more. He might have sleep apnea
or heart failure
brought on by the sleep apnea.