Demographic data and sleep-related symptoms in the patients with PD and controls
| PD | Controls | p Value | |
| n (male/female) | 436 (197/239) | 401 (187/214) | 0.67 |
| Age (years) | 69.3±7.8 | 69.2±8.6 | 0.38 |
| Education (years) | 12.5±2.8 | 12.2±2.8 | 0.10 |
| Caffeine intake, n (%) | 381 (87.4) | 342 (85.3) | 0.38 |
| Caffeine (cup/day) | 2.5±2.0 | 2.5±2.3 | 0.97 |
| Alcohol, n (%) | 196 (45.0) | 217 (54.1) | 0.0081 |
| Smoking, n (%) | 35 (8.0) | 71 (17.7) | <0.0001 |
| PDSS-2 total score | 15.4±9.3 | 9.2±6.0 | <0.0001 |
| PD-related sleep problems, n (%) | 153 (35.1) | 28 (7.0) | <0.0001 |
| ESS total score | 8.4±5.2 | 6.1±3.5 | <0.0001 |
| EDS, n (%) | 165 (37.8) | 62 (15.5) | <0.0001 |
| RBDSQ-J total score | 3.9±2.8 | 1.6±1.8 | <0.0001 |
| pRBD, n (%) | 153 (35.1) | 31 (7.7) | <0.0001 |
ESS, Epworth Sleepiness Scale; RBDSQ-J, REM sleep behaviour screening questionnaire-Japanese version; EDS, excessive daytime sleepiness (ESS ≥10); PD, Parkinson’s disease; PD-SP, PD-related sleep problems (PDSS-2 ≥18); PDSS-2, PD sleep scale-2; pRBD, probable RBD (RBDSQ J ≥5).