Table 2.
Actigraphy variables considered in the factor analysis
| Variable name | Variable description |
|---|---|
| Number of naps | Mean of number of naps per day of duration ≥5 min |
| Minutes napping | Mean of minutes napping per day, considering only naps ≥5 min |
| Mesor* | The middle of the peak, computed as Minimum + Amplitude/2 |
| Pseudo-F* | Pseudo-F goodness of fit statistic from ECM. Higher values indicate better conformity to extended cosine curve |
| Amplitude* | Amplitude from the extended cosine model |
| Beta* | Determines whether the function rises and falls more steeply than the cosine curve. Large values produce nearly square curves |
| Alpha* | Width of peaks relative to troughs from ECM. Large values indicate the peaks are narrow and the troughs are wide; small values indicate the peaks are wide and the troughs are narrow |
| Time in bed | Mean of minutes from bed to wake-up time |
| Time from onset to wake-up (TOW) | Mean of minutes from sleep onset to wake-up time |
| TST | Mean of minutes of sleep from bedtime to wake-up time |
| Bedtime | Mean of bedtime |
| Sleep onset time | Mean of sleep onset time |
| Midpoint (bed interval) | Mean of midpoint of bed to wake-up time |
| Midpoint (onset interval) | Mean of midpoint of sleep onset to wake-up time |
| Wake-up time | Mean of wake-up time |
| Acrophase* | Time of maximum activity from the extended cosine model |
| Up-mesor* | Time of switch from low to high activity (above to below mesor) from the ECM |
| Down-mesor* | Time of switch from high to low activity (below to above mesor) from the ECM |
| Wake after sleep onset | Mean of minutes awake after sleep onset |
| Sleep efficiency | TST/TIB × 100 |
| Sleep maintenance | TST/TOW × 100 |
| Sleep latency | Mean of minutes from bed to sleep onset time |
| Minimum* | Minimum value of activity function from ECM |
| SD wake-up time | Standard deviation of wake-up time |
| SD midpoint (onset interval) | Standard deviation of midpoint of sleep onset to wake-up time |
| SD midpoint time (bed interval) | Standard deviation of midpoint of bed to wake-up time |
| SD sleep onset | Standard deviation of sleep onset time |
| SD bedtime | Standard deviation of bedtime |
*Computed from extended cosine model (ECM).