TABLE 2.
Sleep‐related characteristics of participants
| Chronotype | ||||
|---|---|---|---|---|
| Variable | Morning, N = 326 a | Intermediate, N = 347 a | Evening, N = 138 a | p‐Value b |
| Insomnia symptoms (Yes) | 39 (12%) | 42 (12%) | 34 (25%) | < 0.001 |
| Sleepiness (ESS) | 6.4 (3.7) | 6.0 (3.4) | 6.0 (3.5) | 0.3 |
| Unknown | 0 | 1 | 1 | |
| Sleep quality (PSQI) | 5.1 (3.0) | 5.6 (3.3) | 6.6 (3.4) | < 0.001 |
| Unknown | 7 | 9 | 1 | |
| Hypnotic medication (Yes) | 37 (11%) | 64 (18%) | 42 (30%) | < 0.001 |
| Unknown | 0 | 1 | 0 | |
| Self‐reported sleep duration | 0.061 | |||
| < 6 hr | 74 (23%) | 96 (28%) | 33 (24%) | |
| 6–8 hr | 232 (71%) | 222 (64%) | 87 (63%) | |
| > 8 hr | 20 (6.1%) | 29 (8.4%) | 18 (13%) | |
| PSG total sleep time, hr | 6.1 (0.8) | 6.1 (0.8) | 5.9 (0.8) | 0.047 |
| AHI, events per hr | 13.1 (14.8) | 14.8 (16.5) | 13.6 (15.1) | 0.4 |
| T90, min | 3.3 (13.5) | 5.4 (23.9) | 7.7 (31.7) | 0.13 |
| SE, % | 80.7 (14.1) | 82.0 (19.7) | 81.2 (22.1) | 0.7 |
| SOL, min | 12.9 (12.9) | 17.2 (17.1) | 21.0 (19.6) | < 0.001 |
| WASO, min | 72.1 (38.5) | 70.7 (35.3) | 70.3 (36.7) | 0.8 |
| NREM, % of total sleep | 80.8 (6.3) | 80.9 (5.9) | 82.9 (6.2) | 0.002 |
| REM, % of total sleep | 19.1 (6.3) | 19.1 (5.9) | 17.1 (6.2) | 0.002 |
| Periodic leg movements, events per hr | 9.3 (16.4) | 10.5 (19.3) | 8.5 (16.2) | 0.5 |
| Arousal Index, events per hr | 11.0 (12.9) | 11.3 (13.0) | 12.5 (14.1) | 0.3 |
| Lowest oxygen saturation, % | 85.6 (7.3) | 84.6 (7.8) | 85.2 (7.7) | 0.4 |
| Unknown | 0 | 1 | 1 | |
Abbreviations: AHI, apnea–hypopnea index; ESS, Epworth Sleepiness Scale; NREM, non‐rapid eye movement; PSG, polysomnography; PSQI, Pittsburgh Sleep Quality Index; REM, rapid eye movement; SE, sleep efficiency; SOL, sleep‐onset latency; T90, time SpO2 < 90% saturation; WASO, wake after sleep onset.
a
Mean (SD).
b
One‐way ANOVA.