Table 1.
Demographic characteristics of monozygotic and dizygotic twin pairsa.
| Measure | Total (N = 182) | Monozygotic twins (MZ) (n = 110) | Dizygotic twins (DZ) (n = 72) | pb |
|---|---|---|---|---|
| Age, years | 27.99 ± 7.26 | 29.17 ± 6.86 | 26.19 ± 7.54 | .056 |
| Male, n (%) | 58 (31.9%) | 28 (25.5%) | 30 (41.7%) | .114 |
| Caucasian, n (%) | 142 (78.0%) | 92 (83.6%) | 50 (69.4%) | .122 |
| BMI, kg/m2 | 24.26 ± 4.32 | 24.44 ± 4.72 | 23.99 ± 3.63 | .610 |
| CES-D total scorec | 14.93 ± 3.90 | 14.70 ± 3.66 | 15.28 ± 4.26 | .377 |
| ESS total scored | 5.72 ± 3.30 | 5.39 ± 2.83 | 6.23 ± 3.87 | .152 |
| Global PSQI scoree | 3.50 ± 1.87 | 3.49 ± 1.92 | 3.53 ± 1.80 | .902 |
| Total sleep time (min) | 405.0 ± 59.1 | 398.2 ± 58.6 | 415.5 ± 58.7 | .105 |
| Sleep efficiency (%) | 84.55 ± 10.13 | 83.91 ± 10.08 | 85.53 ± 10.21 | .370 |
| Time in NREM sleep (min) | 315.5 ± 44.2 | 310.0 ± 41.6 | 324.0 ± 46.9 | .069 |
| Number of Arousals | 70.26 ± 31.47 | 71.22 ± 30.27 | 68.79 ± 33.39 | .681 |
| AHI (events/hr) | 1.80 ± 1.40 | 1.64 ± 1.41 | 2.03 ± 1.35 | .119 |
| PLMI (events/hr) | 1.92 ± 5.35 | 2.45 ± 6.29 | 1.12 ± 3.34 | .153 |
Abbreviations: MZ, monozygotic; DZ, dizygotic; BMI, body mass index; CES-D, Center for Epidemiologic Studies Depression Scale; ESS, Epworth Sleepiness Scale; PLMI, periodic limb movement index; PSQI, Pittsburgh Sleep Quality Index; NREM, non-rapid eye movement sleep.
aResults presented as mean ± SD for continuous measures or n (%) for categorical measures.
b p value from mixed linear or logistic model comparing MZ and DZ groups, controlling for possible correlation within MZ and DZ pairs.
c n = 2 missing values.
d n = 7 missing values.
e n = 5 missing values.