Table 2.
Bivariate Correlations Among Primary Study Variables
| 1. | 2. | 3. | 4. | 5. | 6. | 7. | 8. | 9. | 10. | 11. | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. Actigraphy sleep duration | -- | ||||||||||
| 2. Actigraphy sleep efficiency | .52* | -- | |||||||||
| 3. Actigraphy prop. days napped | −.12 | −.15* | -- | ||||||||
| 4. Actigraphy average minutes napped | −.09 | −.13* | .86* | -- | |||||||
| 5. Diary sleep duration | .54* | −.03 | −.01 | −.04 | -- | ||||||
| 6. Diary good sleep quality | .08 | .09 | −.01 | .02 | .09 | -- | |||||
| 7. Diary prop. days napped | −.23* | −.13* | .40* | .43* | −.21* | −.24* | -- | ||||
| 8. Diary average minutes napped | −.24* | −.15* | .43* | .48* | −.21* | −.17* | .91* | -- | |||
| 9. Race | .30* | .19* | −.03 | −.06 | .20* | −.11 | −.11 | −.09 | -- | ||
| 10. BMI | −.05 | −.02 | −.01 | −.08 | .01 | .06 | −.14* | −.11 | −.02 | -- | |
| 11. IL-6 | −.06 | −.05 | .13* | .14* | −.003 | .09 | −.05 | .01 | −.02 | .26* | -- |
| 12. hsCRP | −.02 | −.01 | −.03 | −.03 | .01 | .06 | −.04 | −.03 | .09 | .45* | .46* |
Note. BMI = body mass index; hsCRP = high sensitivity C-reactive protein; IL-6 = interleukin 6; Prop. days napped = proportion of days with at least one nap of 30 minutes or more.
Proportion of days napped and average minutes napped (by actigraphy and diary measures) were square root transformed prior to analysis; BMI, hsCRP, and IL-6 values were natural log transformed prior to analyses.
*
p ≤ .05.