What This Means
People with COPD often sleep poorly, yet sleep is not usually part of how the disease is assessed, and sleep apnoea is typically summarised by one number, the apnoea-hypopnoea index. This study used a home sleep monitor in 205 patients with COPD and combined 15 sleep measurements, including sleep length, sleep stages, oxygen levels at night, breathing interruptions and daytime sleepiness. Statistical clustering sorted patients into five groups: good sleepers, short sleepers, light sleepers with little REM sleep, sleepers with low nighttime oxygen, and sleepers with severe sleep apnoea.
The groups had similar airflow limitation and COPD symptoms, but differed in blood gases, exercise capacity, inflammation, and heart and metabolic disease. Over a median of about 4 years, 28% of the 199 patients followed died. Compared with good sleepers, those with low nighttime oxygen had a higher risk of death after accounting for age, sex and lung function. Untreated severe sleep apnoea patients also had a higher risk after accounting for CPAP-type treatment. The groups were small, so these risk estimates are imprecise.
This research suggests sleep is an important, under-recognised dimension of how COPD varies between patients, and that looking at several sleep features may give information beyond standard lung tests and the apnoea index. The findings come from a single clinical cohort and need to be confirmed in prospective studies before they can guide care.