I'm sorry I don't have any explanations since you only have mild sleep apnea. But I, too, am looking for an explanation for my symptoms, which are very similar to yours. Hopefully someone will respond who can give us the answers we are seeking.
I do have severe sleep apnea and have to wear a CPAP- a machine that forces air into my lungs while I sleep so that my oxygen saturation levels don't fall too far- and usually it works pretty well. But in the last week or so, I sleep all night with my CPAP and then from about 8am to about 3:30pm, I am so sleepy that my eyes are rolling back in my head and I am seriously FIGHTING to stay awake. In fact, I haven't been able to stay awake during those times without fighting sleep with all my energy. I have tried getting up and doing vigorous exercise and listening to loud, rock or dance music, turning the a/c on to get cold, etc. but nothing works. So I end up sleeping all night and most of the day. And you would think that I would not be able to go to sleep at night after sleeping all day, but I do! I'm even sleepy about 11pm or so!
I can't continue on like this. I hope and pray that SOMEONE has some ideas that can help us to function and not to be so sleepy. And also that someone will have an explanation for what is going on with us.
Take care! And good luck to you with your classes. I hope you can get some help SOON.