From the other side of the consultation, briefly. Take it one variable at a time. Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent argument can untangle them after the fact.

SleepDoc_PDX said:

For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.

This is exactly what I could not find anywhere else. Adding it to my notes with a link back to this thread.

Adding the clinical framing, because it changes how the question reads. The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either. Those three things can all be true at once, and most arguments here are two people holding different parts of that.

If somebody has the primary source to hand I would rather cite it than paraphrase it.

KevinCompounds said:

The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either.

Second this. Nothing to add that would improve it.

Moderator note: two posts asking for a source have been merged into one. Please search the thread before asking again.