Table 1.

Demographic and sleep characteristics of the Penn State Cohort (study I)

	Men (n = 609)	Women (n = 715)
Age	49.1 ± 13.8	47.0 ± 13.3
BMI	26.6 ± 4.0	27.1 ± 5.9
TIB (min)	475.4 ± 0.7	477.0 ± 0.6
SL (min)	31.7 ± 1.3	32.7 ± 1.2
WTASO (min)	92.2 ± 2.2	77.9 ± 1.9
%ST	74.0 ± 0.6	76.8 ± 0.5*
%Stage 1	14.1 ± 0.3	5.4 ± 0.2*
%Stage 2	68.2 ± 0.3	71.7 ± 0.3
%SWS	3.0 ± 0.3	5.0 ± 0.2*
%REM	16.7 ± 0.3	17.9 ± 0.3
REM latency (min)	104.9 ± 2.5	138.3 ± 3.0*
A/HI	0.6 ± 0.05	0.3 ± 0.03*

BMI, body mass index; SL, sleep latency; WTASO, wake time after sleep onset; ST, sleep time; SWS, slow wave sleep; REM, rapid eye movement; TIB, time in bed; A/HI, apnea/hypopnea index.

^*P < 0.05.