Table 3.

Results of multiple linear regression models testing for associations between objective sleep properties and demographic and socioeconomic variables among NSHAP study participants (2010-11); models also controlled for BMI category, alcohol consumption, current smoking, and physical activity level (N = 726).

Predictors	Total sleep time (minutes)	WASO (minutes)	Time in bed (hours) (N=591)	Sleep percentage (%)	Sleep fragmentation (%)
	β (SE)	β (SE)	β (SE)	β (SE)	β (SE)
Female gender (males = reference) a	25.8 (7.3)**	4.1 (2.4)	0.79 (0.19)***	0.17 (1.1)	-1.6 (0.45)**
Age (decades)	11.9 (5.2)*	---		-3.1 (0.81)***	0.60 (0.40)
Age effect for men (decades)b (N=342)	---	3.3 (2.0)	0.32 (0.13) *	---	---
Age effect for women (decades)b (N=384)	---	-1.0 (1.5)	-0.22 (0.16)	---	---
pgender*age interaction term	---	0.013	0.001	---	---
Race/ethnicity
Non-Hispanic white	Ref	Ref	Ref	Ref	Ref
Black	-9.8 (9.6)	9.2 (2.8)**	-0.10 (0.31)	-2.9 (1.6)	2.3 (0.62)***
Hispanic	-4.9 (10.6)	-1.1 (3.7)	-0.38 (0.22)	1.6 (2.3)	-0.2 (0.68)
Other	-73.2 (20.1)**	-3.8 (3.9)	0.10 (0.44)	2.4 (3.2)	1.9 (2.0)
Marital status
Married/living with a partner	Ref	Ref	Ref	Ref	Ref
Divorced/separated/never married	-26.2 (10.5)*	0.8 (3.3)	-0.24 (0.18)	-1.0 (1.9)	0.58 (0.95)
Widowed	-7.8 (10.4)	8.6 (2.6)**	-0.2 (0.2)	-4.2 (1.7)*	1.28 (0.60)*
Educational attainment
< High school degree	Ref	Ref	Ref	Ref	Ref
High school degree/some college	-14.3 (9.5)	-10.0 (4.0)*	-0.73 (0.2)***	5.8 (2.3)*	-1.3 (0.88)
Bachelor's degree or more	-12.6 (10.4)	-11.6 (3.4)**	-1.0 (0.23)***	6.1 (2.0)**	-1.55 (0.82)

^*P<=0.05;

^**P <0.01;

^***P<0.001

^aNote that for those models including a gender × age interaction term, the female gender effect refers to those individuals at the youngest ages.

^bThe sex-specific age effects were extracted from sex-stratified models, for ease of interpretation, when there was evidence of sex differences.