Table 2. Descriptive statistics summarizing 2013 and 2014 demographic variables (N = 2,812).

Variables	2013 (n = 1,575)		2014 (n = 1,237)
	N	%	N	%
Difficulty with Alertness
Never, rarely	901	59.63%	1,722	61.35%
Some days	424	28.06%	735	26.18%
Most, every day	186	12.31%	350	12.47%
Nap Frequency
Never, rarely	668	44.09%	1,240	44.03%
Some days	429	28.32%	775	27.52%
Most, every day	418	27.59%	801	28.44%
Sleep Latency
<15 minutes	695	52.93%	1,269	52.22%
15-30 minutes	385	29.32%	720	29.63%
>30 minutes	233	17.75%	441	18.15%
Sleep Quality
Good, Very Good	1,040	68.74%	1,957	69.62%
Fair	349	23.07%	630	22.41%
Very poor, poor	124	8.20%	224	7.97%
Sleep Duration
7-8 hours	818	55.05%	1,508	54.74%
≤5 hours	60	4.04%	119	4.32%
6-7 hours	419	28.20%	769	27.91%
≥ 9 hours	189	12.72%	359	13.03%
Snoring
Never, rarely	1,390	91.87%	2,605	92.84%
Some nights	87	5.75%	143	5.10%
Most, every night	36	2.38%	58	2.07%