. Author manuscript; available in PMC: 2009 Aug 5.

Published in final edited form as: Curr Biol. 2008 Jul 24;18(15):1118–1123. doi: 10.1016/j.cub.2008.06.047

Table 1.

Asymptotic duration (± standard error) of sleep measures in young and older subjects during extended sleep opportunities. Data were fit to the equation: Sleep Measure=Asymptote + b*exp(-(time constant)*day).

Sleep measure	Older All HSD	Younger All HSD	Younger Matched HSD range
HSD range (hr)	7.0 – 9.0	6.1-10.3	7.0 – 9.0
*Per 24 hours*
Total Sleep Time (hr)	7.4 (0.4)	8.9 (0.4)^**	9.2 (0.4)^**
REM sleep (hr)	1.3 (0.1)	2.1 (0.1)^***	2.0 (0.1)^***
All NREM Sleep (hr)	6.1 (0.3)	6.7 (0.4)	7.1 (0.4) ^*
NREM sleep Stage 1 (hr)	1.2 (0.2)	N/A	1.4 (0.1)
NREM sleep Stage 2 (hr)	4.1 (0.4)	4.4 (0.4)	4.6 (0.4)
NREM sleep Stage 3 (hr)	0.6 (0.1)	0.5 (0.1)	0.5 (0.1)
NREM sleep Stage 4 (hr)	0.2 (0.1)	0.6 (0.1)^***	0.5 (0.1)^**
SWS (hr)	0.8 (0.1)	1.1 (0.1)^*	1.1(0.1)
Wake (hr)	8.5 (0.4)	7.0 (0.4)^**	6.7 (0.4)
*Nighttime (12-hour) only*
Total Sleep Time (hr)	6.4 (0.3)	7.9 (0.2)^***	8.1(0.3)^***
REM sleep (hr)	1.2 (0.1)	1.9 (0.1)^***	1.9 (0.1)^***
All NREM Sleep (hr)	5.1 (0.2)	5.9 (0.2) ^**	6.2 (0.2) ^***
NREM sleep Stage 1 (hr)	1.0 (0.1)	1.1 (0.1)	1.1 (0.1).
NREM sleep Stage 2 (hr)	3.5 (0.2)	3.9 (0.3)	4.1 (0.2)
NREM sleep Stage 3 (hr)	0.5 (0.1)	0.4 (0.0)	0.4 (0.1)
NREM sleep Stage 4 (hr)	0.1 (0.1)	0.5 (0.1)^***	0.4 (0.1)^***
SWS (hr)	0.7 (0.1)	0.9 (0.1)^*	0.9 (0.1)
Wake (hr)	5.5 (0.3)	4.0 (0.2)^***	3.8 (0.3)^***
*Daytime (4-hour) only*
Total Sleep Time (hr)	1.2 (0.2)	N/A	N/A

p≤0.05

^**

p≤0.01

^***

p≤0.001 for comparisons versus Older.

N/A indicates no asymptote was statistically fit.