Which is more important/accurate for BBT?

J•B • Mommy of 4.
I've searched for this question because I was sure someone had answered it before but I found lots of conflicting replies.. 
I work nights (12hr shift plus an 1.5hr commute) 3-4 nights a week. I have been temping same time everyday but I've been off for two weeks. Now I'm going back to work and still wanted to know if I could temp on those days as long as I slept for 4+ hours.. 

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