Effects of Between- and Within-Subject Variability on Autonomic Cardiorespiratory Activity during Sleep and Their Limitations on Sleep Staging: A Multilevel Analysis

Table 8

Comparison of sleep staging results (wake/REM sleep/light sleep/deep sleep) using different schemes in correcting the cardiorespiratory parameters.

	PSG	BS	CS1	CS2	CS3
Overall performance
Accuracy, %	—	55.8 ± 9.8	60.4 ± 8.8	62.9 ± 7.8	83.5 ± 14.4
Kappa coefficient	—	0.19 ± 0.10	0.29 ± 0.11	0.35 ± 0.09	0.72 ± 0.23
Sleep stage composition (percentage)
Wake, %	19.8 ± 12.5	19.9 ± 14.4	18.4 ± 4.9	20.6 ± 6.4	19.7 ± 10.7
REM sleep, %	14.0 ± 5.6	0.7 ± 1.0	2.4 ± 2.0	3.0 ± 1.7	10.5 ± 7.8
Light sleep, %	53.4 ± 10.7	74.7 ± 15.1	73.5 ± 8.1	71.0 ± 8.2	59.9 ± 12.0
Deep sleep, %	12.8 ± 7.2	4.7 ± 5.6	5.7 ± 5.2	5.4 ± 4.0	9.9 ± 7.6

Note: BS, baseline with original parameter values without correction; CS1, with correction by fixed effects; CS2, with correction by fixed effects and between-subject random effects; CS3, with correction by fixed effects and within-subject random effect (model residual). For CS2 and CS3, results were obtained when assuming the sleep stages were known, which was usually not the case in practice. For accuracy and Kappa coefficient, significance of difference between using each correction scheme and BS was confirmed with a paired (two-sided) Wilcoxon signed-rank test, all at .