Table 3.
Pearson and Point-Biserial Correlations Between Group, Mediating and Outcome Variables
| DASS | DERS | Group | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Depression | Anxiety | Stress | Non-Accept | Goals | Impulse | Aware | Strategies | Clarity | DERS Total | 0 = HC, 1 = BPD | |
| Insomnia Severity Index | .723** | .776** | .745** | .512** | .562** | .735** | .486** | .758** | .633** | .725** | .720** |
| Pittsburgh Sleep Quality Index | .648** | .705** | .656** | .433** | .508** | .675** | .441** | .663** | .568** | .646** | .617** |
| Epworth Sleepiness Scale | .085 | .172 | .184 | .093 | .099 | .066 | .224 | .061 | .081 | .111 | .056 |
| Bedtime | −.206 | −.126 | .021 | −.030 | − .030 | − .072 | − .166 | − .114 | −.167 | − .103 | − .072 |
| Rise Time | .214 | .282* | .369** | .365** | .259* | .294* | .309** | .290* | .258* | .351** | .372** |
| Time in Bed | .455** | .450** | .398** | .445** | .325** | .407** | .520** | .445** | .462** | .503** | .497** |
| Total Sleep Time | .383** | .354** | .308** | .297* | .267* | .307* | .364** | .380** | .362** | .386** | .261** |
| Sleep Onset Latency | −.025 | −.009 | −.014 | .119 | −0.003 | .050 | .022 | −.009 | .008 | .051 | .107 |
| Sleep Efficiency | .048 | .007 | .006 | −.063 | .025 | .010 | −.054 | .062 | .016 | .008 | −.020 |
| Wake After Sleep Onset | .015 | .055 | .057 | .126 | .014 | .060 | .156 | −.001 | .055 | .069 | .104 |
| Bedtime (SD) | .351** | .442** | .426** | .211 | .199 | .303* | .035 | .371** | .230 | .297* | .345** |
| Rise Time (SD) | .331** | .351** | .343** | .266* | .315** | .279* | .044 | .318** | .166 | .308* | .394** |
| Time in Bed (CV) | .118 | .158 | .190 | .123 | .171 | .049 | −.038 | .120 | −.030 | .086 | .125 |
| Total Sleep Time (CV) | .062 | .112 | .132 | .136 | .096 | .007 | −.020 | .046 | −.025 | .045 | .047 |
| Group (0 = HC, 1 = BPD) | .833** | .795** | .782** | .648** | .666** | .869** | .524** | .874** | .755** | .880** | – |
Note. All values represent Pearson correlation co-efficient, except for correlations involving Group where Point-Biserial correlations are presented instead given the categorical nature of the Group variable. DASS Depression Anxiety Stress Scale. DERS Difficulties in Emotion Regulation Scale. HC Healthy comparison. BPD Borderline personality disorder. SD Standard deviation. CV Coefficient of variation * p < .05. ** p < .01