Air Carrier Captain reports calling in fatigued during the trip pairing following a continuous duty overnight; when maintenance delays push the duty day beyond the originally scheduled 13 hours.

Narrative

I was scheduled for a continuous duty overnight which went on duty in the early evening and remained on duty until early morning the next day. I was also scheduled to start a two day trip the following morning. The first day of my two day trip consisted of approximately 13 hours of duty. Although I was tired at the start of my two day trip; I determined I was safe to fly. We completed our first two legs; a round trip; without incident. On arrival we had a plane swap; and the plane we swapped into was on maintenance. As the duty day continued I grew more fatigued. I came to the determination that I was too fatigued to complete my remaining three flights safely and notified scheduling. Scheduling accommodated me by putting me in a hotel; and we planned to resume my trip the following day after I got the needed rest. I believe my fatigue resulted primarily from the shift change in duty time resulting from my continuous duty overnight completed one day prior to the start of this trip. I essentially worked third shift on Day 1 to Day 2; and began a first/second shift trip on Day 3. I slept approximately 3 hours at the completion of the overnight; and had a very restless night on Day 2's night as a result of not sleeping at my normal sleep hours during my trip. It is my opinion that continuous duty overnights should not be paired next to normal trip pairings. Continuous duty overnight pairings should be paired only with other continuous duty pairings. I believe it is too much to ask your body to shift schedules so dramatically and expect you to be safe to operate an aircraft at 100%.