Table 3.

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

		Quartiles of magnesium intake (mg/1,000 kcal/day)				P trend
		Q1 (lowest)	Q2	Q3	Q4 (highest)
Outcome: sleep quality (ORs of better sleep quality score)
CES-D <16		1(Ref.)	1.13 (0.96, 1.32)	1.15 (0.95, 1.39)	1.30 (1.04, 1.63)	0.02
CES-D ≥16		1(Ref.)	0.81 (0.59, 1.11)	0.71 (0.48, 1.05)	0.79 (0.48, 1.29)	0.34
p interaction		0.005
Outcome: sleep duration (ORs compared to the reference group: 7–9 h)
CES-D<16	<7 h vs. ref	1(Ref.)	0.98 (0.81, 1.18)	0.73 (0.59, 0.91)	0.64 (0.49, 0.82)	<0.0001
	>9 h vs. ref	1(Ref.)	0.77 (0.42, 1.42)	0.62 (0.26, 1.47)	0.73 (0.27, 1.95)	0.39
CES-D≥16	<7 h vs. ref	1(Ref.)	1.02 (0.70, 1.49)	1.24 (0.77, 1.99)	0.66 (0.38, 1.15)	0.33
	>9 h vs. ref	1(Ref.)	1.22 (0.45, 3.30)	1.86 (0.48, 7.18)	1.21 (0.20, 7.19)	0.68
p interaction		0.07 (<7 h) 0.14 (>9 h)

All models were constructed using general estimation equations with adjustment for covariates in Model 3, Table 2. P for trend and p for interaction were examined using the medians of magnesium quartiles for sleep quality and using the continuous variable of ranks of magnesium intake (1 to 4) for sleep duration.

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