Table 2.
Sleep-Related Characteristics of Final Sample
| Sleep Regularity Groups | ||||
|---|---|---|---|---|
| Variable | Regular, N = 200 | Mildly irregular, N = 2011 | Severely irregular, N = 2011 | P-value2 |
| Sleep regularity index | 84.8 (3.4) | 76.1 (2.6) | 61.9 (8.9) | <0.001 |
| PSG total sleep time (hours) | 6.2 (0.9) | 5.9 (0.9) | 5.9 (1.0) | 0.008 |
| Actigraphy sleep duration (hours) | 7.1 (0.7) | 7.0 (0.8) | 6.6 (1.3) | <0.001 |
| AHI (events/hour) | 10.0 (10.6) | 15.5 (17.1) | 16.4 (18.1) | <0.001 |
| Time Spo2 < 90% saturation (min) | 1.0 (3.4) | 4.6 (16.5) | 9.6 (38.2) | 0.002 |
| Sleep efficiency (%) | 81.7 (17.4) | 80.1 (21.5) | 78.4 (14.5) | 0.2 |
| Sleep onset latency | 69.4 (40.1) | 78.1 (44.1) | 73.7 (44.0) | 0.13 |
| Wake after sleep onset (min) | 15.7 (16.4) | 17.7 (18.1) | 16.8 (18.6) | 0.5 |
| NREM (%) | 80.3 (5.6) | 81.9 (6.7) | 82.3 (6.4) | 0.003 |
| N1 (%) | 15.4 (7.6) | 18.7 (12.4) | 18.5 (10.8) | 0.003 |
| N2 (%) | 50.3 (7.8) | 48.4 (9.6) | 49.5 (9.8) | 0.10 |
| N3 (%) | 14.5 (8.0) | 14.9 (9.4) | 14.3 (9.2) | 0.8 |
| REM (%) | 19.7 (5.6) | 18.1 (6.7) | 17.7 (6.4) | 0.003 |
| Insomnia symptoms (ISQ) | 24 (12%) | 29 (14%) | 36 (18%) | 0.2 |
| Chronotype (MEQ) | 0.002 | |||
| Morning | 90 (45%) | 84 (42%) | 70 (35%) | |
| Evening | 18 (9.0%) | 31 (16%) | 47 (24%) | |
| Intermediate | 92 (46%) | 85 (42%) | 81 (41%) | |
| Unknown | 0 | 1 | 3 | |
| Sleepiness (ESS) | 15 (7.5%) | 20 (10%) | 17 (8.5%) | 0.7 |
| Unknown | 0 | 1 | 1 | |
| Poor self-reported sleep quality (PSQI) | 70 (35%) | 76 (39%) | 100 (51%) | 0.003 |
| Unknown | 1 | 6 | 6 | |
1Mean (SD).
2One-way ANOVA.
PSG, polysomnography; AHI, apnea hypopnea index; Sp02, oxygen saturation; T90, Time; SpO2, 90% saturation; NREM, non-rapid eye movement; N1, NREM stage 1; N2, NREM stage 2; N3, NREM stage 3; REM, rapid eye movement; ISQ, Insomnia Symptom Questionnaire; MEQ, “Morning Eveningness” Questionnaire; ESS, Epworth Sleepiness Scale; PSQI, Pittsburgh Sleep Quality Index.