Table 2.

Linear regression models predicting reported habitual sleep hours by average sleep duration measured using wrist actigraphy. Regression is a modified version of errors-in-variables regression. Data collected in 2000-2004 from the Chicago site of CARDIA.

Stratification variable	Reliability†	Bias (at 6 hours)		Calibration		Discrimination		Predicted reported sleep hours at
		Intercept (hours)	95% CI	Beta	95% CI	r2	95% CI	5 hours measured sleep	7 hours measured sleep
Full Sample (n=647)	0.70	0.80	0.71, 0.88	0.51	0.35, 0.67	0.20	0.11, 0.30	6.29	7.31
Male	0.75	0.82	0.71, 0.92	0.46	0.28, 0.63	0.21	0.10, 0.33	6.36	7.27
Female	0.62	0.75	0.60, 0.90	0.59	0.29, 0.89	0.19	0.06, 0.34	6.16	7.34
Black	0.61	0.63*	0.47, 0.79	0.38	0.11, 0.65	0.07**	0.01, 0.19	6.25	7.01
White	0.73	0.88*	0.77, 0.99	0.54	0.37, 0.70	0.29**	0.18, 0.42	6.34	7.42
Age ≤ 42 years	0.72	0.88	0.74, 1.02	0.38	0.19, 0.57	0.11*	0.03, 0.22	6.50	7.26
Age > 42 years	0.69	0.74	0.64, 0.85	0.62	0.41, 0.83	0.29*	0.16, 0.42	6.12	7.36
Non-obese	0.70	0.90**	0.80, 1.00	0.47	0.31, 0.63	0.19	0.10, 0.29	6.43	7.37
Obese	0.69	0.61**	0.45, 0.77	0.54	0.19, 0.89	0.19	0.05, 0.36	6.07	7.15
Low depression score	0.71	0.86**	0.76, 0.96	0.50	0.33, 0.67	0.20	0.11, 0.30	6.36	7.36
High depression score	0.65	0.52**	0.32, 0.72	0.47	0.11, 0.83	0.16	0.02, 0.36	6.05	6.99
Good-excellent	0.70	0.80	0.71, 0.88	0.57	0.42, 0.72	0.24*	0.15, 0.33	6.22	7.37
Poor/Fair	0.67	0.54	0.11, 0.97	0.06	-0.60, 0.73	0.00*	0.00, 0.17	6.48	6.60
No college degree	0.69	0.73	0.61, 0.85	0.43	0.22, 0.63	0.12*	0.04, 0.23	6.30	7.16
College degree	0.69	0.83	0.71, 0.95	0.59	0.37, 0.81	0.30*	0.16, 0.45	6.24	7.42
Low income	0.68	0.76	0.59, 0.94	0.36	0.11, 0.61	0.08**	0.01, 0.20	6.41	7.12
High income	0.69	0.75	0.64, 0.85	0.67	0.47, 0.87	0.34**	0.22, 0.40	6.08	7.42
Low apnea risk	0.68	.090**	0.80, 1.00	0.48	0.33, 0.63	0.18	0.11, 0.28	6.42	7.38
High apnea risk	0.75	0.17**	-0.10, 0.44	0.46	0.10, 0.82	0.17	0.02, 0.39	5.71	6.63
Low sleepiness	0.65	0.87**	0.76, 0.97	0.48	0.30, 0.66	0.16	0.08, 0.26	6.39	7.35
High sleepiness	0.77	0.56**	0.35, 0.76	0.47	0.19, 0.75	0.18	0.04, 0.35	6.08	7.03
Low sleep efficiency	0.67	0.93*	0.71, 1.15	0.42*	0.16, 0.67	0.11*	0.03, 0.23	6.51	7.34
High sleep efficiency	0.62	0.60*	0.45, 0.76	0.78*	0.54, 1.03	0.32*	0.18, 0.47	5.82	7.39
Low sleep variability	0.90	0.78	0.68, 0.87	0.52	0.39, 0.66	0.24	0.14, 0.35	6.25	7.29
High sleep variability	0.46	0.83	0.68, 0.99	0.50	0.00, 1.00	0.14	0.01, 0.36	6.33	7.36

^†Reliability of 3 day weighted average as a measure of true 30-day average

^*p<0.05 for comparison of intercept, beta coefficient or r².

^**p<0.01 for comparison of intercept, beta coefficient or r².