I have a similar natural rhythm, or I should say "had". For the first year, especially the first few months, it was a godsend (for my wife, especially), but now that we're in a fairly consistent sleep routine with our two year old (~8pm-7am), I've shifted to something more like 8pm-1am out of necessity.

Although... I was up until 4am and got up at 6:30am and feel surprisingly great, so it still happens from time to time. :)