Table 4.

Discordant twin pair analyses including same-sex twin pairs, odds ratios (ORs) with 95% confidence intervals (CIs)

	Whole sample, age and sex adjusted	All same-sex pairs (MZ + DZ)	DZ same-sex	MZ
	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
Time pressure (n = 919)a
Twice a month or less	Ref
Once a week or more	0.92 (0.86–0.99)	0.90 (0.73–1.11)	0.75 (0.56–1.01)	1.10 (0.81–1.49)
Sleep problems (n = 1057)a
Twice a month or less	Ref
Once a week or more	1.31 (1.20–1.43)	1.62 (1.24–2.12)	1.64 (1.12–2.38)	1.60 (1.10–2.35)

MZ monozygotic, DZ dizygotic twin pairs

^an = 919–1057 discordant pairs