Table 2.
Iowa Sleep Disturbances Inventory (ISDI) Scale Correlations in the Scale Development Sample 2
| ISDI Scale | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. Initial Insomnia | .— | ||||||||||
| 2. Anxiety at Night | .48 | .— | |||||||||
| 3. Fragmented Sleep | .45 | .36 | .— | ||||||||
| 4. Nonrestorative Sleep | .38 | .25 | .25 | .— | |||||||
| 5. Light Sleep | .35 | .28 | .44 | .12 | .— | ||||||
| 6. Irregular Schedule | .32 | .21 | .15 | .39 | .10 | .— | |||||
| 7. Fatigue | .27 | .35 | .25 | .57 | .17 | .34 | .— | ||||
| 8. Sensations at Night | .17 | .17 | .24 | .23 | .19 | .10 | .29 | .— | |||
| 9. Nightmares | .16 | .31 | .26 | .17 | .18 | .06 | .17 | .29 | .— | ||
| 10. Movement at Night | .04 | .07 | .14 | .10 | .01 | .03 | .05 | .27 | .24 | .— | |
| 11. Excessive Sleep | −.01 | .15 | .05 | .27 | −.04 | .20 | .48 | .13 | .19 | .05 | .— |
Note. n = 335. Correlations of |.50| and greater are in bold. Correlations of |.11| and greater are significant at p < .05.