You can get a different opinion for each reply with this one. We work a 24/7 op using 2 days/2 nights/4 off cycle, with a 0730/1930 changeover.
Advantages are: you only have to get up early for two days, then you can have a lie-in; after your first night, you've only got one more, then you're off; 4 days leave/holiday gives you 12 days off work.
Disadvantages: you always finish on a night duty, so your 4 days off is really only about 3 and a half.
With this pattern you don't really have to worry about circadian rythems, as you are not doing it long enough for them to start changing.