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

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

 CorrelationP value
PSG nighttime
 N1− 0.2270.503
 N1 + N20.3360.313
 N2 + N3 + REM0.7000.021*
 N3 + REM0.4830.132
 Arousal index0.0001.000
 Frequency of sleep stage shift− 0.0270.946
PSG daytime
NSCAN nighttime
 Awakenings− 0.5400.086
  1. The arousal index indicates arousal numbers per hour. The frequencies of sleep stage shift indicate transition numbers per hour among wake, REM, and NREM
  2. Abbreviations: TST total sleep time (N1 + N2 + N3 + REM), SE sleep efficiency (TST/540 for nighttime, TST/900 for daytime)
  3. *Statistically significant at p < 0.05