Table 2 Sleep parameters and respiratory indices of the described diagnostic groups.
| Variable | Normal | Primary snoring | Mild obstructive sleep apnoea | Moderate‐to‐severe obstructive sleep apnoea | Central sleep apnoea |
|---|---|---|---|---|---|
| n | 49 | 7 | 12 | 11 | 12 |
| Total sleep time (min) | 449 (42) | 456 (51) | 444 (67) | 464 (54) | 475 (50) |
| Stage 1 | 3.0 (2.5) | 1.6 (2.0) | 2.0 (2.2) | 1.9 (1.6) | 1.8 (1.8) |
| Stage 2 | 44.1 (7.2) | 37.6 (7.4) | 39.9 (6.1) | 42.8 (7.7) | 41.7 (8.6) |
| Stage 3 | 9.8 (4.7) | 9.7 (4.6) | 10.9 (5.6) | 11.6 (3.9) | 10.5 (4.3) |
| Stage 4 | 22.0 (6.4) | 27.0 (7.9) | 23.9 (5.2) | 21.7 (8.2) | 22.4 (6.9) |
| REM | 21.1 (5.1) | 24.1 (6.8) | 23.2 (4.2) | 21.1 (5.9) | 23.6 (7.5) |
| Sleep efficiency (%) | 84.7 (6.8) | 85.4 (5.7) | 84.0 (9.2) | 86.1 (7.3) | 88.0 (5.6) |
| REM latency (min) | 139.8 (57.3) | 126.6 (78.5) | 122.0 (53.0) | 162.9 (66.7) | 124.0 (58.3) |
| Sleep latency (min) | 26.6 (22.4) | 23.4 (13.0) | 44.0 (36.2) | 36.7 (28.1) | 21.2 (19.8) |
| Central apnoea index | 0.33 (0.37) | 0.83 (0.61) | 0.92 (1.13) | 1.20 (0.97) | 1.57 (2.39) |
| Obstructive apnoea index | 0.07 (0.18) | 0.17 (0.31) | 0.42 (0.52) | 0.85 (1.84) | 0.16 (0.25) |
| OAHI | 0.25 (0.41) | 0.80 (0.65) | 3.13 (1.32)* | 10.70 (2.88)*† | 0.22 (0.26)‡§ |
| Central apnoea hypopnea index | 0.59 (0.53) | 1.49 (0.92) | 1.74 (1.69) | 3.19 (4.54)* | 4.32 (6.13)* |
| SaO2 nadir (%) | 91.5 (2.6) | 89.3 (2.0) | 88.8 (3.28) | 87.8 (6.8) | 82.2 (4.76)*§ |
| Mean SaO2 (%) | 96.9 (0.7) | 96.3 (0.5) | 96.6 (1.6) | 96.7 (0.6) | 96.4 (1.0) |
| Oxygen desaturation index | 0.4 (0.4) | 1.2 (0.9) | 2.4 (2.5)* | 3.2 (5.5) | 5.0 (8.1)* |
| % of total sleep time with SaO2 ⩾95% | 98.7 (1.5) | 97.4 (1.9) | 89.4 (25.5) | 94.6 (7.8) | 93.6 (4.8)* |
OAHI, Obstructive apnoea hypopnoea index; REM, rapid eye movement; SaO2, oxygen saturation.
Values are given as mean (SD).
Stage 1– 4 and REM sleep are all presented as a percentage of total sleep time.
*p<0.05 with normal group.
†p<0.05 with primary snoring.
‡p<0.05 with mild obstructive sleep apnoea (2⩽ OAHI<5).
§p<0.05 with moderate‐to‐severe obstructive sleep apnoea (OAHI⩾5).