The shelf covers each of these properly: CPAP Flow Limitation: The Hidden Metric Beyond AHI — the metric that explains most of this thread. RERA and Flow Limitation: The Events That Don't Show in Your AHI — arousals that never become scored events. UARS (Upper Airway Resistance Syndrome): The Diagnosis Your AHI Misses — the diagnosis that a good AHI can hide. Still Tired on CPAP With Good Numbers? Reasons and Next Steps — the overview, if you want one page rather than four. Nothing on SomniTalk is medical advice. Talk to your own clinician before changing therapy.