Old news
Been there, done that. The BBC article is just rehashing Gil Levin's tired old claim that few folks in the planetary science community take seriously. The best that can be said for Mr. Levin's experiment is that the results were inconclusive. Hopefully, future missions will answer the question in better fashion.
It is noteworthy that both the NASA and ESA missions rejected Mr. Levin's proposed "new experiment."
As for Mr. Miller's claim about "circadian rythms," its fifteen minutes of "fame" has long since expired. The idea has never gotten much traction.