It can, and treatment compliance is what decides it. Treated sleep apnea with documented CPAP use is frequently underwritten at standard rates; untreated or non-compliant apnea is assessed considerably more cautiously.
Sleep apnea is one of the clearest examples of underwriting rewarding management rather than penalising diagnosis.
Compliance data is real data
Modern CPAP machines record usage — hours per night, nights used, residual events. That data is genuinely available and carriers do ask about it.
Consistent documented use is strong evidence of a controlled condition and frequently produces standard or better rates. A prescribed machine sitting unused is a worse file than no diagnosis at all, because it shows a known risk going unmanaged.
What else is weighed
Severity from the sleep study, measured by the apnea-hypopnea index. Whether it is obstructive or central — central apnea is often secondary to cardiac disease and is assessed with that in mind. And the conditions that travel with it: build, cholesterol, blood pressure and diabetes cluster with sleep apnea often enough that carriers look for them.
What to supply
Your sleep study report with the AHI, your CPAP compliance download if you have one, and a current weight. Where weight loss has improved or resolved the apnea, a repeat sleep study documenting that is worth obtaining before applying.
The full treatment of this topic is on COPD and respiratory.