Table 3.
Absolute within pair phenotype differences in monozygotic and dizygotic twin pairs.
| Measure | Absolute within pair differencea | ||
|---|---|---|---|
| MZ twins (N = 110) | DZ twins (N = 72) | pb | |
| Arousal Index | 3.75 ± 3.38 | 3.99 ± 4.47 | .7689 |
| Average arousal duration | 0.64 ± 0.50 | 0.71 ± 0.67 | .5921 |
| Average arousal intensity scale | 0.50 ± 0.42 | 0.86 ± 0.73 | .0114 |
| Slope of ΔHR per arousal intensity | 0.57 ± 0.44 | 0.63 ± 0.48 | .5435 |
| Arousal intensity threshold of ΔHR | 0.67 ± 0.54 | 0.99 ± 0.88 | .0563 |
| Average ΔHR | 2.18 ± 1.86 | 3.13 ± 2.43 | .0370 |
| ΔHR at arousal intensity scale 4 | 1.55 ± 1.31 | 1.98 ± 1.25 | .1226 |
| ΔHR at arousal intensity scale 5 | 1.98 ± 1.44 | 2.27 ± 1.24 | .3220 |
| ΔHR at arousal intensity scale 8 | 3.43 ± 2.46 | 3.55 ± 2.29 | .8259 |
Abbreviations: MZ, monozygotic; DZ, dizygotic; ΔHR, heart rate response to arousal;
aValues represent mean ± standard deviation of the absolute value of the within pair difference in the indicated measure;
bp value from t-test comparing within pair differences between MZ and DZ twin pairs.