Table 1.
Demographic and clinical characteristics
| Characteristic | N a | Mean ± SD or No. (%) |
|---|---|---|
| Age (years) | 1635 | 78.9 ± 5.2 |
| Females | 1098 (67.2) | |
| Non-white | 1629 | 390 (23.9) |
| BMI (kg/m2) | 1,635 | 30.2 ± 6.1 |
| BMI ≥30 | 752 (46.0) | |
| Smoking status | ||
| Never | 1,606 | 834 (51.9) |
| Former | 722 (45.0) | |
| Current | 50 (3.1) | |
| 3MSE | 1635 | 91.6 ± 5.4 |
| <89 | 439 (26.9) | |
| CES-D b | 1553 | 9.2 ± 8.4 |
| ≥16 | 1592 | 312 (19.6) |
| Number of medical conditions c | 1631 | 1.5 ± 1.0 |
| Hypertension | 1621 | 1151 (71.0) |
| Diabetes mellitus | 1628 | 414 (25.4) |
| Symptomatic arthritis | 1625 | 318 (19.6) |
| Chronic lung disease d | 1627 | 253 (15.6) |
| Coronary artery disease | 1627 | 129 (7.9) |
| Stroke | 1628 | 109 (6.7) |
| Heart failure | 1622 | 71 (4.4) |
| Number of prescription medications used | 1633 | 5.4 ± 3.3 |
| Polypharmacy | 1150 (70.4) | |
| CNS-based | 655 (40.1) | |
| Caffeine/energy drink use | 1635 | 1302 (79.6) |
| Reduced health status | 1631 | 271 (16.6) |
Abbreviations: BMI, body mass index; CES-D, Center for Epidemiologic Studies Depression Scale; CNS, central nervous system; COPD, chronic obstructive pulmonary disease; 3MSE, Modified Mini-Mental Status Exam; SD, standard deviation.
N varies as a consequence of missing values.
If the CES-D score was ≥ 16 but in the presence of missing questionnaire items, participants were classified as having high levels of depressive symptoms (i.e., included as a categorical variable), whereas their continuous scores were considered missing (i.e., not included in the calculation of mean values).
These were self-reported, physician diagnosed, and selected on the basis of their known associations with sleep-wake disturbances.1,2,4,7,8
Asthma, chronic bronchitis, emphysema, or COPD.