I am downloading data from my CPAP to the ResMed software and to SleepyHead. I noticed that the events count is different between the two programs. In the example images, the same event is interpreted as Hypopnea by SleepyHead but ResMed does not count it at all.
Another issue that can be seen in these images: Resmed shows the air flow centered on zero. That makes sense as breathing in and out obviously include a reverse of direction. Sleepyhead, however, has a negative bias and ALL the breathing sequence appears to be in the negative numbers. The third image shows how at an obstractive event, were there is no air flow, SleepyHead calculates a sharp increase in tidal volume. I would assume that the tidal volume should decrease to zero instead.
It is possible that Sleepyhead needs some calibration.