SleepDoc_PDX said:

Practical: whatever you change, write down the date and the reason.

Correct as far as it goes. The part it does not cover is what to do when the honest answer is "not enough data", which is more often than anyone likes.

Worth separating that from the pharmacology, which this thread keeps folding into the same question. They behave differently and the advice does not transfer.

SleepDoc_PDX said:

Practical: whatever you change, write down the date and the reason.

Bookmarking. The distinction being drawn above is the one nobody else makes. Taking it to my next appointment.

From the other side of the consultation, briefly. The version of this that has an answer is narrower than the version being asked. Narrow it and it becomes tractable; leave it broad and the thread will produce nine confident and incompatible replies.

Found this through search years later and it is still the best discussion of the question, so adding one thing. Give anything pharmacological four weeks before you judge it, and give anything measured weekly a four-point rolling average before you call it a trend.

Dr.SleepRoch said:

The version of this that has an answer is narrower than the version being asked.

Coming at Dr.SleepRoch’s question from a different direction. Start from the measurement rather than the conclusion. Almost every disagreement here turns out to be two people measuring different things and comparing the numbers anyway.