Circadian Rhythms, Shift Work, & Apnea

I've worked night shift (7P-7A) for nearly 10 years. I started using CPAP in November 2011. My day-time sleeping varies from decent to sucky (even with CPAP). I take Ambien; without it, I don't even sleep at night (been that way for many, MANY years).

While CPAP has seemed to improve my night-time sleeping, day-time sleeping still lacks. I'm sure it has to do with circadian rhythms and such (I don't stay on a night schedule 24/7 - doesn't work with family life). About 50% of the time, I'll wake up with a tremendous and nearly incurable headache (after day-time sleep).

Does anyone have any suggestions on improving day-time sleeping?

Thanks in advance.

I thought you was writing about me, 10 years on nightshift and my sleep patterns are all over the place so much so that when its dark I have trouble sleeping yet daytime I have no problems try looking up S.W.S.D. or Light/Dark Therapy they maybe some good points of intrest for you.

http://en.wikipedia.org/wiki/Shift_work_sleep_disorder