Percentual proportion of sleep cycles in controls (panel A) and seniors (panel B) and sleep frag-mentation due to respiratory related arousals (panels C, D) of patients with OSA. Data are matched for apnea/hypopnea index - AHI. Panels A, B: Patients in the elderly group had lowered proportion of slow-wave NREM3 sleep. *p=0,005 NREM3%, controls vs. seniors. Panels C, D: In younger people with OSA, arousal index on diagnostic polysomnography night almost corresponded with their apnea/hypopnea index. With advancing age, the number of spontaneous arousals has an increasing tendency and adds to overall sleep fragmentation of seniors with OSA.