Table 2.

Correlations among Rest-Activity Rhythm Stability Measures and Sleep Duration, Sleep Efficiency, Physical Activity, and Global PSQI

Variable	Correlate	Young adults		Older adults
		R	95% CI	R	95% CI
Amplitude	Sleep duration	−0.04	[−0.61, 0.56]	0.20	[−0.14, 0.53]
	Sleep efficiency	0.23	[−0.37, 0.65]	0.33	[0.15, 0.52]*
	Physical activity	−0.12	[−0.47, 0.59]	0.25	[−0.19, 0.56]
	Global PSQI	−0.16	[−0.51, 0.25]	0.14	[−0.11, 0.34]
F-statistic	Sleep duration	0.21	[−0.41, 0.73]	0.15	[−0.18, 0.38]
	Sleep efficiency	0.43	[−0.03, 0.68]	0.43	[0.24, 0.62]*
	Physical activity	−0.27	[−0.55, 0.30]	0.35	[0.00, −0.57]
	Global PSQI	−0.19	[−0.47, 0.07]	−0.02	[−0.25, 0.22]
Interdaily stability	Sleep duration	0.03	[−0.54, 0.59]	0.20	[−0.05, 0.44]
	Sleep efficiency	0.23	[−0.25, 0.52]	0.30	[0.05, 0.53]*
	Physical activity	−0.11	[−0.33, 0.18]	0.17	[−0.16, 0.40]
	Global PSQI	−0.01	[−0.33, 0.21]	0.22	[−0.09, 0.43]
Intradaily variability	Sleep duration	−0.39	[−0.67, −0.06]	−0.26	[−0.49, 0.02]
	Sleep efficiency	−0.11	[−0.48, 0.27]	−0.22	[−0.49, 0.07]
	Physical activity	0.00	[−0.25, 0.20]	−0.11	[−0.33, 0.18]
	Global PSQI	0.09	[−0.27, 0.45]	−0.25	[−0.45, −0.04]*
Relative amplitude	Sleep duration	0.62	[0.41, 0.81]*	0.56	[0.36, 0.70]*
	Sleep efficiency	0.70	[0.49, 0.86]*	0.58	[0.28, 0.75]*
	Physical activity	−0.52	[−0.78, −0.06]*	−0.13	[−0.47, 0.18]
	Global PSQI	−0.18	[−0.52, 0.16]	−0.02	[−0.33, 0.27]

Correlations were performed using bootstrapped confidence intervals with jackknife adjustment. All neuropsychological measures were reported as standardized z-scores. * indicates p < 0.05.