. Author manuscript; available in PMC: 2015 Oct 1.

Published in final edited form as: J Sleep Res. 2014 Apr 15;23(5):499–507. doi: 10.1111/jsr.12150

TABLE 2.

Estimated Median Duration of Poor or Average Sleep Bouts by Sleep Group

	Good Sleeper	Insomnia	Z Statistic	p-value¹
Unadjusted Model	1.18	2.82	−5.72	<0.001
Adjusted Model by Time in Bed
25^th percentile – 7.6 hours	1.14	2.42
50^th percentile – 8.4 hours	1.18	2.77	−3.28	0.001
75^th percentile – 9.3 hours	1.22	3.17

p-value is from Wald test of sleep group variable in unadjusted model and of interaction term between sleep group and covariate of interest in adjusted models