The figures, for anyone assembling their own picture. One practical note: write down what you did and when, before you need it. Reconstructing a timeline from memory three months later is how people end up unable to answer the one question that would have resolved it.

A narrower follow-up, since the general answer is now clear:

Was that from a primary source or from a summary of one?

SleepDoc_PDX said:

One practical note: write down what you did and when, before you need it.

This is where I part company with the consensus forming above. Pushing back on the anecdote-stacking. Twenty people reporting the same thing is twenty samples from the same self-selected pool, not twenty independent confirmations.

SleepDoc_PDX said:

One practical note: write down what you did and when, before you need it.

Agreed, and the size of the effect matters as much as its existence. Something real and small gets treated here as though it were real and decisive.

Found this through search years later and it is still the best discussion of the question, so adding one thing. For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine. Half the figures circulating in this community trace back to a secondary summary that dropped a qualifier.