Table 2.
Mobility, physical inactivity, and sleep-wake disturbances
| Characteristic | N a | Mean ± SD or No. (%) |
|---|---|---|
| Mobility | ||
| 400m walk time (minutes) | 1635 | 8.5 ± 1.9 |
| Slow gait speed (400m gait speed <0.8 m/s) | 712 (43.5) | |
| Short Physical Performance Battery (SPPB) | 7.4 ± 1.6 | |
| Moderate-to-severe mobility impairment (SPPB ≤ 7) | 731 (44.7) | |
| Physical inactivity | ||
| Sedentary time (%) b | 1173 | 77.0 ± 8.0 |
| Sleep-wake questionnaires c,d | ||
| Insomnia Severity Index (ISI) e | 1578 | 5.8 ± 5.1 |
| Insomnia (ISI ≥8) | 1610 | 532 (33.0) |
| Subgroup of ISI ≥8 | 500 | 12.1 ± 3.6 |
| Epworth Sleepiness Scale (ESS) f | 1589 | 6.1 ± 3.9 |
| Daytime drowsiness (ESS ≥10) | 1591 | 288 (18.1) |
| Subgroup of ESS ≥10 | 286 | 12.5 ± 2.5 |
| Pittsburgh Sleep Quality Index (PSQI) g | 1620 | 5.9 ± 3.8 |
| Poor sleep quality (PSQI >5) | 1629 | 778 (47.8) |
| Subgroup of PSQI >5 | 769 | 9.2 ± 2.8 |
| Berlin Questionnaire: high risk of sleep apnea h | 1613 | 530 (32.9) |
Abbreviations: SD, standard deviation; 400m, 400 meter.
N varies as a consequence of participants being excluded because of poor testing performance, missing values, or subgroup analysis.
Percent of accelerometer wear time with activity <100 counts/minute, averaged across days. Limited to participants with at least 5 days of wear time and at least 10 hours on each day.
The results of the ISI, ESS, and PSQI questionnaires were reported in three ways: 1) overall mean score, 2) number of participants who had a sleep-wake disturbance, and 3) mean score for the subgroup who had a sleep-wake disturbance. The BQ was reported only as a dichotomous variable.
Sample sizes for the ISI, ESS, and PSQI also varied according to the reported analysis. In particular, if the ISI, ESS, or PSQI score met criteria for a sleep-wake disturbance but the questionnaire was otherwise incomplete, a sleep-wake disturbance was still established (reported as a categorical variable), whereas the continuous score was considered missing (not included in the calculation of mean values). For example, the sample size was 1610 for estimating the frequency of insomnia (ISI ≥8) but only 1578 when calculating the overall mean ISI. Similarly, the calculation of the mean ISI among the 532 participants who had insomnia (ISI ≥8) was based on a sample size of only 500 participants.
ISI ranges from 0–28, with higher scores signifying more severe insomnia.
ESS ranges from 0–24, with higher scores signifying more severe daytime drowsiness.
PSQI ranges from 0–21, with higher scores signifying a worse sleep quality.
Required ≥2 positive categories on the Berlin Questionnaire.