I am sure it is quite alarming to see your husband go through the breathing difficulty. I would suggest that he get a general medical evaluation and then consider the following possibilities. Since he has a high BMI he may have obstructive sleep apnoea. The other symptom that presents like this is described as paroxysmal nocturnal dyspnea, which may be heart, related. Some throat problems may also look like this. You could see what your internal medicine doctor thinks and then share this email and see how they want to proceed. Sleep apnoea will be detected by a sleep study and the other problems will need to be evaluated by appropriate specialists. Hope things get better soon and you find the answer.