Table 2. Sleep Parameters.

Data are derived from polysomnography and represent minutes (mean + SEM) unless indicated otherwise, for the Morning Sleep (0800 – 1600; n = 14) and Evening Sleep (1400 – 2200; n = 16) groups. Note that prior to Day Sleep 1, the Morning Sleep group had been awake for 26 hours while the evening sleep group for 32 hours. The symbols ‘*’ and ‘∼’ represent a comparison to baseline sleep at the p < 0.01 and p < 0.05 level respectively (paired t-test). The symbol ‘#’ represents a comparison between the Evening and Morning Sleep groups at the p<.01 (unpaired t-test). Sleep latencies were log-transformed for statistical comparisons. The reported comparisons between Sleep groups and Sleep Conditions were done when the corresponding main effect or interaction in the two-way ANOVA with the factors Sleep Group and Sleep Condition were significant.

Sleep Parameters	Baseline	Day sleep 1	Day sleep 2	Day sleep 3
TST
Evening	431.6 ± 12.8	424.4 ± 12.5	410.3 ± 12.5	428.9 ± 12.8
Morning	421.3 ± 13.4	403.6 ± 13.8	398.4 ± 13.8	417.61 ± 13.4
Sleep Efficiency
Evening	89% ± 3%	88% ± 3%	86% ± 3%	89% ± 3%
Morning	88% ± 3%	84% ± 3%	83% ± 3%	87% ± 3%
Sleep Latency
Evening	28.4 ± 3.3	7.1 ± 3.2 *	14.6 ± 3.2 *	13.1 ± 3.3 *
Morning	32.5 ± 3.4	8.0± 3.5 *	10.5 ± 3.4 *	11.6 ± 3.4 *
WASO
Evening	18.0 ± 12.6	45.6 ± 12.3 ∼	52.5 ± 12.3 ∼	35.6 ± 12.6
Morning	24.0 ± 13.1	67.0 ± 13.5 *	69.7 ± 13.5 *	49.1 ± 13.1
Stage 1
Evening	35.9 ± 3.8	27.1 ± 3.7 *	34.1 ± 3.7	35.3 ± 3.8
Morning	35.7 ± 4.0	29.8 ± 4.1	31.9 ± 4.1	37.6 ± 4.0
Stage 2
Evening	224.8 ± 10.5	225.4 ± 10.3	213.3 ± 10.3	227.7 ± 10.5
Morning	232.1 ± 11.0	208.5 ± 11.3 *	195.9 ± 11.3 *	205.7 ± 11.1 *
SWS
Evening	73.4 ± 8.1	96.4 ± 8.0 *	80.1 ± 8.0	76.2 ± 8.1
Morning	60.3 ± 8.6	78.6 ± 8.7 *	68.6 ± 8.7	69.8 ± 8.6
REM
Evening	98.0 ± 5.5	75.8 ± 5.3 *	82.7 ± 5.3 *#	90.1 ± 5.5
Morning	93.2 ± 5.7	86.8 ± 5.9	102.2 ± 5.9 #	104.5 ± 5.7