Becoming awake by 3:30-4AM

[RPM1965]

Hello,
For the second night in a row I have gone to bed around 10:30-10:45 in the evening, then for some reason I awake at between 3 and 4 in the morning. The first of the two nights I was able to fall back to sleep within the hour but the second morning (this morning)I woke up at 4 and couldn't get back to sleep. I have had the cpap machine since May of this year and have noticed just recently that my sleeping habits fluctuate from sleeping right through till 6ish ( which is when I need to get up to start my day) or I fall short a couple hours and struggle to fall back asleep. Anybody else having these issues ever once in a while or frequently?
Thanks in advance.

[LSAT]

That's a common occurrence for me...to bed by 10:30..wake up about 4:00....Sleep on and off for the next 2 hours. Been that way for years. I can be fully functional with 6-61/2 hours sleep. Melatonin helps.