I Suffer From Excessive Daytime Sleepiness. I Have Structured And

I suffer from excessive daytime sleepiness. I have structured and consistent good sleep time (10 hour window), I have been tested for sleep apnea (I have a CPAP). I sleep 7-8 hours. I use light therapy for 15 minutes when I wake up. I feel OK for the first couple of hours after waking in the morning, but then I start feeling very sleepy. This persists throughout the day. If I break down and take a nap (which I usually fight against doing) I go to sleep in minutes, and wake after about an hour and a half. I feel OK again but then the sleepy feelings come again in a couple of hours. I am eating healthy, I drink no caffeine or alcohol ever. I suspected some "mild" form of narcolepsy, but I thought they would find that when screening for the CPAP.