Table 3.
Sleep and Rest-Activity Rhythm Characteristics of Young and Older Adults
| Young adults | Older adults | p | |
|---|---|---|---|
| N | 46 | 57 | |
| Sleep measures | |||
| Sleep time (mean [SD]) | 400.33 (94.99) | 403.49 (84.68) | 0.860 |
| Sleep efficiency (mean [SD]) | 81.72 (6.78) | 80.49 (8.91) | 0.442 |
| Onset latency (mean [SD]) | 20.48 (13.59) | 28.92 (20.20) | 0.018* |
| Total activity (mean [SD]) | 322,947.97 (183,583.88) | 252,918.64 (89,505.82) | 0.014* |
| Cosinor rest-activity measures | |||
| Amplitude (mean [SD]) | 1.61 (0.29) | 1.58 (0.34) | 0.598 |
| Width (alpha) (mean [SD]) | −0.48 (0.16) | −0.40 (0.26) | 0.050 |
| Slope (beta) (mean [SD]) | 6.63 (2.74) | 14.02 (26.63) | 0.070 |
| Mesor (mean [SD]) | 0.94 (0.16) | 0.95 (0.19) | 0.768 |
| Acrophase (phi) (mean [SD]) | 16.45 (1.43) | 14.76 (1.63) | <0.001*** |
| Up-mesor (mean [SD]) | 8.58 (1.73) | 7.10 (1.78) | <0.001*** |
| Down-mesor (mean [SD]) | 24.31 (1.41) | 22.43 (1.83) | <0.001*** |
| Minimum (mean [SD]) | 0.14 (0.18) | 0.16 (0.17) | 0.444 |
| F-statistic (mean [SD]) | 3216.56 (1613.86) | 3612.04 (1624.19) | 0.230 |
| Non-parametric rest-activity measures | |||
| Interdaily stability (IS) (mean [SD]) | 0.42 (0.11) | 0.54 (0.12) | <0.001*** |
| Intradaily variability (IV) (mean [SD]) | 0.87 (0.25) | 0.85 (0.27) | 0.746 |
| Relative amplitude (RA) (mean [SD]) | 0.84 (0.14) | 0.86 (0.11) | 0.341 |
| L5 (mean [SD]) | 16.46 (16.77) | 11.97 (12.07) | 0.143 |
| M10 (mean [SD]) | 172.61 (46.04) | 158.76 (49.12) | 0.177 |
* indicates p < 0.05, ** indicates p < 0.01, *** indicates p < 0.001.