Table 8.
Results of hierarchical regression analyses predicting sleep quality from the two subscales of the SHI
| Step | Predictor | β (Final) | ΔR 2 | Total R 2 |
|---|---|---|---|---|
| 1. |
Age |
-.01 |
|
|
| |
Sex |
.06 |
|
|
| |
Education |
−1.15 |
|
|
| |
Pain duration |
.00 |
.07* |
|
| 2. |
Pain intensity |
.14 |
|
|
| |
Depression |
.83*** |
|
|
| |
Pain-related anxiety |
.07 |
.55*** |
|
| 3. |
Sleep disturbing B/E |
.17 |
|
|
| Irregular sleep-wake schedule | -.67* | .02* | .63*** |
Note: *p < .05, ***p < .001. SHI: Sleep Hygiene Index; B/E: behavior and environment. Sex, education, and pain duration were not normally distributed. Thus, normality was further checked through histograms of the standardized residuals [32], and Q-plots and P-plots [33]. These tests supported the assumption of normality.