I've worked this shift pattern before, and found it very difficult. They call it a 'continental' shift pattern in the UK - it's not a new thing, 'cos the job I'm thinking of was 30 years ago. Switching from sleeping during the night to sleeping during the day is okay if you're on permanent nights, but trying to change every couple of weeks can be impossible (I remember once failing to get any real sleep during the day, having to spend the next 12 hours at work, and then collapsing on my way home the next day.)