If it's something that would happen in slack time, there's plenty of that around at that ungodly hour of the morning! We have a few scheduled jobs that take about two minutes in total to run; the next thing that happens is the first (transaction) dump of the day, which is a biggie (containing all the changes created by optimization jobs...) Apart from that, the system is fairly quiet until about 8ish.
This whole thing seems to be shrouded in secrecy. Apart from that one technet article, and a few bits that make oblique reference to ghost cleanup, there's precious little out there. Why is the Microsoft SQL Server development team not responding? Where are you, guys? Other SQL Server product companies read these pages! c'mon!