Welcome! I was DXed with sleep apnea in 2006, but I'm sure I had it for at least 40 years. I use the CPAP machine, and my AHI is down around 1 event per hour.

I've been taking Nuvigil to combat daytime sleepiness, and I use a SAD therapy light.

Sometimes I do slip into a somewhat biphasic pattern. It seems that a supper with lots of carbs (and sugar) promotes this.

As well, the full Moon can bring about alertness in me at night. This starts about one week before the full moon and lasts roughly two weeks. I tend to sleep deeply all night during a new moon.