Table 1.

Age differences in sleep architecture.

	Younger Adults – Median [1st quartile; 3rd quartile]	Older Adults – Median [1st quartile; 3rd quartile]	z	p
TST (min)	457.00 [420.0; 508.5]	417.50 [370.75; 447.25]	2.60	0.009
WASO (min)	8.5 [1.75; 12.75]	20.5 [9.50; 32.25]	−3.56	<0.001
Stage 1 (%)	4.31 [3.07; 5.88]	7.57 [4.72; 10.20]	−3.19	0.001
Stage 2 (%)	50.69 [44.96; 56.92]	63.99 [61.09; 69.96]	−5.45	<0.001
SWS (%)	20.56 [16.62; 26.61]	3.80 [0.00; 12.67]	5.38	<0.001
REM (%)	24.49 [21.6; 26.69]	21.10 [17.01; 24.53]	2.29	0.022

Note. z and p-values were derived from non-parametric Mann-Whitney U tests comparing sleep parameters between younger and older adults. TST: total sleep time; WASO: wake after sleep onset; SWS: slow-wave sleep; REM: rapid eye-movement sleep.