Table 5.

Multivariable-adjusted ORs and 95% CIs of sleep outcomes by quartiles of calcium-to-magnesium ratio levels stratified by depression status

		Quartiles of calcium-to-magnesium ratio				P trend
		Q1 (lowest)	Q2	Q3	Q4 (highest)
Outcome: sleep quality (ORs of better sleep quality score)
CES-D <16		1(Ref.)	1.00 (0.86, 1.16)	1.00 (0.86, 1.17)	0.99 (0.84, 1.17)	0.97
CES-D ≥16		1(Ref.)	0.96 (0.71, 1.30)	0.96 (0.69, 1.32)	1.09 (0.76, 1.54)	0.65
p interaction		.91
Outcome: sleep duration (ORs compared to the reference group: 7–9 h)
CES-D <16	<7 hrs vs. ref	1(Ref.)	0.98 (0.83, 1.15)	1.00 (0.84, 1.18)	1.09 (0.91, 1.31)	0.29
	>9 hrs vs. ref	1(Ref.)	1.03 (0.47, 2.25)	1.43 (0.68, 3.02)	2.49 (1.23, 5.01)	0.008
CES-D ≥16	<7 hrs vs. ref	1(Ref.)	1.21 (0.83, 1.77)	0.81 (0.54, 1.21)	1.22 (0.78, 1.90)	0.70
	>9 hrs vs. ref	1(Ref.)	0.53 (0.18, 1.62)	0.70 (0.22, 2.18)	0.89 (0.25, 3.18)	0.92
p interaction		0.79 (<7 h) 0.16 (>9 h)

All models were constructed using general estimation equations with adjustment for covariates in model 3, Table 3. P for trend and p for interaction were examined using the medians of Ca:Mg quartiles for sleep quality and using the continuous variable of ranks of Ca:Mg (1 to 4) for sleep duration.

Abbreviations: Ca, calcium; CES-D, Center for Epidemiologic Studies Depression Scale; CI, confidence interval; h, hours; Mg, magnesium; OR, odds ratio; Q, quartile; ref, reference.