And tell Calvin it is his health, not yours. Lecture time:
The muscles in our throat and our tongue are voluntary muscles. Meaning we control them the same way we control our fingers. So as we go to sleep, so do they. For some people, for various reasons, these muscles and surrounding tissues start to collapse, taking up space. This narrows the airway and is called a hypopnea. Eventually, the airway collapses completely, shutting off airflow. This is an apnea event.
Each time he stops breathing, his body is deprived of oxygen. Not just his brain, but his entire body. His brain screams for him to wake up. His chest is straining. Nothing comes in. Nothing goes out. Until finally he twitches hard enough or his brain screams loud enough or something and he wakes up enough to open the airway on his own. He falls back asleep and the process happens all over again. Rinse. Repeat.
Meanwhile, with air not coming in, air isn't going out. Various stuff is building up in the blood stream and isn't completely exchanged by the lungs due to the repeated apnea events.
He's also not sleeping well. The brain needs sleep for a reason.
He's not getting the right sleep. We need REM sleep for a reason, too.
Eventually, all that oxygen deprivation causes damage. Subtle at first. High blood pressure. Diabetes. Heart issues. Memory issues. Brain function. One doesn't die of untreated sleep apnea really. One dies a slow death from multiple sources.
So tell Calvin to get over his precious self and grasp this by the horns. Or not. YOU CANNOT DO IT FOR HIM. You just can't. You can encourage. You can be there. You can love him despite the hose on his nose. But it really is up to him.