| Baseline | Air | Oxygen | p Value* | NIV | p Value† | |
| TST (min) | 337 (46) | 331 (58) | 328 (39) | 0.55 | 306 (26) | 0.22 |
| SE (% TIB) | 86 (6) | 82 (11) | 82 (10) | 0.89 | 78 (9) | 0.38 |
| Sleep latency (min) | 20 (23) | 16 (20) | 18 (15) | 0.46 | 13 (13) | 0.84 |
| Stage 1+2 (%TST) | 62 (11) | 60 (11) | 58 (12) | 0.32 | 59 (11) | 0.65 |
| Stage 3+4 (%TST) | 17 (9) | 20 (7) | 23 (10) | 0.2 | 19 (7) | 0.28 |
| REM (%TST) | 21 (7) | 20 (8) | 20 (7) | 0.78 | 22 (7) | 0.09 |
| WASO (min) | 39 (27) | 58 (42) | 53 (34) | 0.5 | 77 (33) | 0.18 |
| AHI (events/h) | 10 (16) | 4 (6) | 4 (5) | 0.82 | 2 (1) | 0.19 |
| AI (events/h) | 12 (5) | 10 (3) | 8 (3) | 0.55 | 12 (6) | 0.41 |
| PLMI (events/h) | 5 (10) | 5 (6) | 5 (8) | 0.82 | 14 (21) | 0.21 |
Values are mean (SD).
*Mean difference from baseline (oxygen vs air).
†Mean difference from baseline (NIV vs air).
AHI, apnoea–hypopnoea index; AI, arousal index; NIV, non-invasive positive pressure ventilation; PLMI, periodic limb movement index; REM, rapid eye movement; SE, sleep efficiency; stage 1+2, total stage 1 and 2 sleep; stage 3+4, total stage 3 and 4 sleep; TIB, time in bed; TST, total sleep time; WASO, wakefulness after sleep onset.