A B767 Captain called off a trip fatigued because the trip bidding software did not take into account circadian rhythm when transitioning from one bid month's last trip to the next month's first trip.

Narrative

If you look at my schedule; from the second half of Dec/08 to the first half of Jan/09; it is obvious that this schedule; though technically legal; is completely unsafe. The current monthly bidding process; which is endorsed by this company's management; does not take into account circadian rhythm; which now has taken its toll on me. I will be unable to fly my next trip due to fatigue. I went to domicile management in the morning at approximately XA30 after completing my trip. I conversed with management. They all supported my position. They said they would try to obtain a paid vacation drop to solve my fatigue issue. Several hours later he called to tell me that he was unable to get me a vacation drop. When the company does then cover the trip; it is clear to me that the company's interest is only covering the trip in the cheapest way possible and is not interested in solving a serious safety issue. So I believe the company is employing a tactic that goes back to the 1930's called pilot pushing. It is time that the FAA takes a stand in favor of safety; as the NTSB has been advocating for sometime; rather than be controlled by the current political climate.