Validity of an under-mattress sensor for objective sleep measurement in critically ill patients: a prospective observational study

Table 4 Spearman’s rank correlation coefficient with objective sleep parameters and the RCSQ

	Correlation	P value
PSG nighttime
SE(=TST)	0.000	1.000
N1	− 0.227	0.503
N2	0.727	0.015*
N3	0.191	0.574
REM	0.486	0.130
N1 + N2	0.336	0.313
N2 + N3 + REM	0.700	0.021*
N3 + REM	0.483	0.132
Arousal index	0.000	1.000
Frequency of sleep stage shift	− 0.027	0.946
PSG daytime
SE(=TST)	0.082	0.818
NSCAN nighttime
SE(=TST)	0.500	0.121
Awakenings	− 0.540	0.086

The arousal index indicates arousal numbers per hour. The frequencies of sleep stage shift indicate transition numbers per hour among wake, REM, and NREM
Abbreviations: TST total sleep time (N1 + N2 + N3 + REM), SE sleep efficiency (TST/540 for nighttime, TST/900 for daytime)
*Statistically significant at p < 0.05

ISSN: 2052-0492