Table 2.

Nocturnal objective and subjective baseline sleep parameters in young, middle-aged, and older subjects

	Young Mean (SD)	Middle-Aged Mean (SD)	Older Mean (SD)	Effect of Age	Middle-Aged vs. Young	Older vs. Young	Older vs. Middle-Aged
Objective (PSG) sleep measures
Total sleep time (min)	433.5 (23.7)	409.9 (40.9)	390.4 (38.5)	P < 0.0001	P = 0.0042	P < 0.0001	P = 0.025
Latency to persistent sleep (min)	20.6 (16.0)	16.6 (12.8)	19.2 (24.8)	NS	NS	NS	NS
Awakenings (number)	20.1 (6.4)	22.9 (6.6)	27.9 (11.8)	P < 0.001	P = 0.152	P < 0.001	P = 0.020
Wake after sleeponset (min)	21.0 (15.9)	49.9 (31.3)	70.7 (36.7)	P < 0.0001	P < 0.0001	P < 0.0001	P = 0.0041
Stage 1 (min)	28.1 (14.3)	29.0 (14.1)	26.7 (10.5)	NS	NS	NS	NS
Stage 2 (min)	198.9 (28.7)	211.8 (32.5)	204.5 (32.0)	NS	(P = 0.079)	NS	NS
Stage 3 (min)	43.5 (23.9)	37.4 (11.4)	45.6 (12.8)	NS	NS	NS	NS
Stage 4 (min)	75.0 (21.7)	47.9 (28.3)	38.6 (26.0)	P < 0.0001	P < 0.0001	P < 0.0001	NS
Slow wave sleep (min)	118.4 (32.5)	85.3 (30.3)	84.2 (32.6)	P < 0.001	P < 0.001	P < 0.001	NS
Slow wave activity (μV2)	3280 (1412)	1923 (836)	1754 (746)	P < 0.001	P < 0.001	P < 0.001	NS
REM sleep (min)	87.9 (17.2)	83.9 (26.0)	75.0 (21.2)	P = 0.0377	NS	P = 0.0113	NS
Subjective sleep measures
Total sleep time (h)	7.25 (0.89)	7.29 (0.62)	7.12 (1.06)	NS	NS	NS	NS
Sleep onset latency (min)	30.3 (32.3)	15.5 (14.8)	40.2 (109.0)	NS	NS	NS	NS
Number of awakenings	2.2 (1.6)	2.9 (2.0)	2.4 (2.0)	NS	NS	NS	NS
Total duration of awakenings (min)	14.4 (25.6)	28.1 (27.3)	59.3 (114.5)	P = 0.0124	NS	P = 0.0033	P = 0.0499
Quality of sleep (mm; more is worse)	46.6 (20.1)	46.4 (23.4)	54.4 (19.9)	NS	NS	NS	NS
Refreshed upon awakening (mm; more is better)	52.8 (17.6)	61.3 (22.7)	48.8 (20.8)	P = 0.0355	(P = 0.0636)	NS	P = 0.0126

For objective measures: N = 41, 31, 31 for the young, middle-aged, and older subjects, respectively. For subjective measures: N = 44, 35, 31. min = minutes. Please note that Lights out was 23:00 and Lights on at 07:00 in all 3 age groups