Table 2.

Sleep variables derived from visual scoring (n = 14; 2 nights per subject)

	Night 1		Night 2		Paired Wilcoxon test	Correlations
	MD	Range	MD	Range
% stage N1 sleep	8.3	1.7–16.0	8.3	4.5–16.5	n.s.	0.75**
% stage N2 sleep	40.4	34.3–61.0	46.4	36.2–53.6	n.s.	0.68**
% stage N3 sleep	26.2	13.6–35.0	26.6	15.8–35.1	n.s.	0.64*
% stage R sleep	20.8	12.6–28.8	19.8	12.9–27.8	n.s.	0.57*
% stage N sleep	70.4	62.7–79.8	72.2	61.1–79.3	n.s.	0.76**
Wake after sleep onset (min)	27.4	12.7–128.3	18.3	4.0–72.3	n.s.	n.s.
Sleep latency (min)	23.2	0–62.0	16.0	6.7–43.7	n.s.	n.s.
R sleep latency (min)	140.7	53.0–215.7	143.2	51.3–178.3	n.s.	n.s.
Total sleep time (min)	442.2	388.3–502.3	477.3	385.0–521.7	Z = −2.04*	n.s.
Sleep efficiency (%)	90.5	72.0–96.8	92.0	77.6–98.0	n.s.	n.s.

Percentages of stage N1, N2, N3, R, and N refer to total sleep time. Sleep latency is defined as the first occurrence of N2. Sleep efficiency is total sleep time as % of time in bed. Stage N sleep refers to stage N2 plus stage N3. MD, median. Paired Wilcoxon tests are based on between-subjects comparisons (night 1 vs. night 2). Correlations are calculated between the 2 nights.

^*P < 0.05;

^**P < 0.01.