Table 1.
Summary of feature groups used in this study. Total movement and duration of movement during the SPT-window and percent of activity at night were computed using GGIR-extracted features, rather than extracted directly. We computed 323 features using known methods and propose 25 novel features to characterize sleep and temperature in this study.
| Feature Group | Type | Brief Description | Number of Features |
|---|---|---|---|
| Sleep | Basic sleep | Summary statistics of sleep duration, time of sleep onset and offset, sleep period time window (SPT-window) | 58 |
| Sleep efficiency | Ratio of time sleeping to time spent in bed | 8 | |
| Night-waking | Movement or duration of waking during the SPT-window, percent of activity at night | 31 | |
| Circadian rhythm | Inter-daily stability and intra-daily variability | 2 | |
| Physical Activity | Activity | Light activity bouts (LIGB), blocks of vigorous activity or moderate-to-vigorous physical activity (MVPA) | 169 |
| Sustained inactivity bouts (SIB) | Inactivity bouts not during sleep period and SIBD | 27 | |
| L5 and M5 h | Five hours of day with highest (M5) and lowest (L5) acceleration | 28 | |
| Novel | Sleep | WE–WD difference, onset before 12 a.m., trend in sleep variables | 6 |
| Temperature | Temp. during sleep: mean, std., ApEn, max. rate of increase/decrease, h after onset of max/min. Temp. over 24 h: min, max, ApEn, min-max difference. Sleep–wake temp. diff. | 19 |