Reading through your letter, I will try to answer this question the best I can without knowing how old your husband is, what kind of medical problems he has, or
how much he used to sleep. That being said, if your husband never used to sleep this much and is otherwise healthy, the first thing I would do is to take him to his health care provider for an evaluation. From what you say, he is getting at least 13+ hours of sleep a day, and that would be especially signigicant if he used to sleep 5 hours a day. Depression, sleep apnea, medication side effects (including pain meds, muscle relaxants, antihistamines), chronic pain, fibromyalgia, lupus, anemias, autoimmune disorders, infections, heart problems, or neurological problems all need to be thoroughly ruled out as a possibility for his increased need to sleep. He should have an extensive physical examination and labwork at the very least to see if anything is wrong. You should schedule this appointment as soon as possible, as many of these problems can get worse if left untreated.
Now, if your husband has been very ill and sleepy for some time, it sometimes takes a while for people to build back up their strength, so sleeping alot is not abnormal. If your husband has dementia and has been slowly declining over time, this may be a sign of progression of the disease. Again, I would check with your health care provider, as they would know if this is something to be concerned about. Hopefully, this answer has helped to give you some guidance on how to help him. Good luck!