A320 Captain reports calling in fatigued after crew scheduling calls to reset his 0200 short call reserve to a PM departure; after sleeping 10 hours.

Narrative

At 0209 [hours]; Crew Scheduling called and said they were resetting my 'rest' from a 0200 short call to fly [a five hour trip with a PM departure]. I informed the Crew Scheduling representative that I had gone to bed very early the day prior; because I knew they were going to call me around 0200 as they did the previous day. I had almost 10 hours of sleep at the time of the 0209 phone call and was ready to fly. I kindly asked the representative; if I didn't get any additional sleep what time they needed me to call-in 'fatigued' so they could 're-crew' the trip. She told me to call about four hours prior to takeoff. She also said she would inform the next Scheduler coming on duty about my sleep situation. I was unable to get anymore sleep and called in 'fatigued' at [the requested time]. For the record; it is almost impossible to go back to sleep after sleeping for almost 10 hours. The human body is not a machine that can be reset with unreasonable sleep patterns at a moment's notice. Crew scheduling and the Company wasted a perfectly rested asset; because their scheduling computer stated this rest change was legal.