Table 4.

Interaction effects between short sleep and having restless/disturbed nights on the hazard of CHD

Exposure	Unadjusted	Adjusted for confoundersa	Adjusted for confounders & mediatorsa,b	No.
> 6 h sleep and no sleep problems	1.00	1.00	1.00	2335
< 6 h sleep only	1.04 (0.82, 1.31)	1.01 (0.80, 1.28)	0.98 (0.77, 1.25)	794
Restless/disturbed nights only	1.21 (1.05, 1.40)	1.23 (1.07, 1.43)	1.17 (1.01, 1.35)	3893
< 6 h sleep – disturbed nights	1.55 (1.33, 1.81)	1.45 (1.24, 1.70)	1.28 (1.08, 1.51)	2122
Interaction between short sleep hours and sleep problems using ALL CHD events
P value for multiplicative interaction	0.12	0.24	0.46	9144
RERI	0.30 (0.01, 0.59)	0.21 (-0.08, 0.49)	0.12 (-0.16, 0.40)	9144
Interaction between short sleep hours and sleep problems using verified CHD events
P value for multiplicative interaction	0.02	0.03	0.10	9429
RERI	0.46 (0.14, 0.77)	0.37 (0.06, 0.68)	0.26 (-0.04, 0.57)	9429

Data are presented as relative risk (95% confidence interval).

^aConfounders include all of the sleep variables, age, sex, ethnicity, employment grade, car access, and housing tenure;

^bMediators include self-rated health status, total cholesterol concentration, hypertension, body mass index, diabetes, smoking, alcohol consumption, vigorous and moderate exercise, and fruit and vegetable consumption.

CHD refers to coronary heart disease; RERI, relative excess risk due to interaction.