CPAP and APAP combination.

I'm using PB420E and I set my unit at 10 cm in CPAP mode at 8 p.m. (bedtime) and at 10cm-14cm range in AUTO mode at 12 a.m. It also automatically adjusts according to the time setting the unit is set, and this combination works indeed fine with me and makes me feel totally refresh when I get up in the morning. I feel comfortable in my first few hours of my sleep while in the CPAP mode, but at midnight where I perhaps change position most of the time I can verify using my software that most of the AHI changes and I need the auto pressures. Has anyone ever tried this sort of CPAP/APAP combination in your unit. 420E is capable of this.