Table 3.
Results of fixed-effects for linear mixed-effects model of mood level from smartphone-measured and time variables. The measure for nighttime stillness was excluded from the otherwise maximal random-effects structure.
| Fixed-effect | Estimate | Standard error |
t value (degrees of freedom) |
P value |
| Mean mood (intercept) | 5.056 | 0.174 | 28.973 (49.0) | <.001 |
| Day of study (semester) | −0.059 | 0.261 | −0.226 (47.0) | .82 |
| Day of week (coded 0-6, Monday-Sunday) | 0.040 | 0.076 | 0.528 (257.0) | .60 |
| Sleep duration | 0.072 | 0.030 | 2.451 (52.0) | .02 |
| Daytime activity | 0.097 | 0.032 | 3.062 (50.4) | .004 |
| Nighttime stillness | 0.040 | 0.026 | 1.528 (1881.5) | .13 |