When to use or not to use a cpap mask

My wife has been diagnosed with CPAP and uses a cpap equipment. She has been tolerating it but she takes naps during the day on the couch. A doctor told her as long as she uses it for five hours or more a night, she can sleep without the mask during the day. A sleep technicians told her she should wear the mask whenever she sleeps more that 20 minutes or sleeps so that she dreams; she should wear a mask. Well which way is the better way. I would appreciate anyone to elaborate on this. A supportive husband in Brooklyn, New York City. Thank you

I used to nap without my mask, too. But the more I thought about it and the damage it causes me, I finally decided to wear a mask whenever I sleep. It's not just about getting enough sleep, it's the side effects that apnea causes that is worry some. The last two times I napped without my CPAP, I had the same dream. It was a Star Trek episode and Spock was telling Captain Kirk: "We've entered an interference zone and we have to get the ship out of here!" I awoke then gasping for breath. When you stop breathing, your heart starts racing trying to get oxygen to the brain. When that doesn't work, your body gives you a jolt of adrenaline to make you gasp and start breathing again. Adrenaline irritates your arteries, which is a dangerous thing, and your body then lays down cholesterol over the irritation. I had my sleep study done in March of 2005 and started using my CPAP machine every night from then on. In December of 2005, I had an emergency quadruple by-pass due to my clogged heart arteries. My problem was only discovered when I asked my doctor if I could switch blood pressure medications. As soon as I got off Atenolol, my angina was discovered--caused by those clogged arteries.
When I picked up my latest model of CPAP machine in February of 2015, I was told that there is a 100% correlation between sleep apnea and atherosclerosis. If you have sleep apnea, you have clogging of the arteries. A nap may produce negligible results, but why do anything to jeopardize your health long term? I had no good answer and simply started using my machine. I can just put my mask on, lay on my side with a pillow over my head to make it dark and quickly fall asleep. My new machine tracks how much sleep I get and adds the nap time into its calculations so my results are more accurate. I like getting those scores of 99 and 100.