@bjbarry Some should probably follow that advice, especially if they're gaining weight, not sleeping more than six hours routinely, have brain fog, memory lapses, or have cranky hearts with atrial fibrillation or SVT. However, if a patient is a regular user of a PAP machine, and the morning report of the previous night's events show an AHI of less than 5.0, the medicos and insurers call that 'successfully treated.' So, my feeling, and it's only that, not advice, is that if a person uses their machine every night, and they have an AHI that runs between, say, 1.5 and 4.9 events, they probably don't need a sleep lab refresher. That said, there is often room for improvement if one wants to fiddle a bit, either with the comfort settings, the pressure settings, a different pillow, a different mask, maybe a heated 'Climateline' hose if they've never tried one, maybe taping one's mouth or using a chin strap....there are strategies to getting the higher AHI down to less than 3 events per hour which might be beneficial in the long run.

I do agree that 20 years is a long time, and if the person's AHI is showing a rising trend over the past year or so, it would very much be my recommendation to attempt another over night sleep lab.