Table 2.

List of significant features (prior to multiple comparison correction) reflecting group tendencies in sleep efficiency, slow EEG activity in N2, and inter-hemispheric EEG coherence in REM sleep between subjects with positive (n = 82) and with negative cognitive change (n = 85). Because none of the tendencies remained significant after Bonferroni–Holm correction, they should not be considered as stand-alone features but combined in a multivariate approach

Feature		Cognition + Mean ± SD	Cognition − Mean ± SD	p	Corrected α-level
Sleep macrostructure
Total W duration (min)		55.1 ± 49.8	69.0 ± 45.0	0.026	0.00072
Relative W duration (%)		12.9 ± 10.6	16.4 ± 10.6	0.016	0.00066
Relative N2 duration (%)		47.7 ± 11.3	44.2 ± 12.1	0.028	0.00075
Sleep efficiency (%)		84.4 ± 10.9	80.7 ± 11.2	0.018	0.00068
Spectral EEG power during N2 sleep
Slow waves (0.5–1.5 Hz)	at F3	93.5 ± 70.7	117.3 ± 87.4	0.022	0.00070
Slow waves (0.5–1.5 Hz)	at F4	99.1 ± 76.4	121.4 ± 88.2	0.028	0.00074
Slow waves (0.5–1.5 Hz)	at C3	64.1 ± 48.5	74.9 ± 47.2	0.044	0.00079
Slow waves (0.5–1.5 Hz)	at C4	64.0 ± 45.5	77.9 ± 46.0	0.016	0.00065
Slow waves (0.5–1.5 Hz)	at O1	17.2 ± 15.3	25.8 ± 19.4	0.001	0.00064
Slow waves (0.5–1.5 Hz)	at O2	21.0 ± 21.2	26.2 ± 19.2	0.047	0.00081
Delta (1.5–4 Hz)	at O1	28.3 ± 26.3	36.2 ± 23.1	0.024	0.00071
EEG coherence during REM sleep
Delta (1.5–4 Hz)	at C3-C4	0.82 ± 0.09	0.78 ± 0.11	0.021	0.00069
Delta (1.5–4 Hz)	at O1-O2	0.67 ± 0.13	0.62 ± 0.17	0.017	0.00068
Theta (4–7.5 Hz)	at C3-C4	0.75 ± 0.12	0.71 ± 0.12	0.032	0.00077
Alpha (7.5–11 Hz)	at C3-C4	0.66 ± 0.14	0.61 ± 0.14	0.030	0.00076
Sigma (11–15 Hz)	at C3-C4	0.63 ± 0.15	0.56 ± 0.14	0.017	0.00067
Beta (15–30 Hz)	at C3-C4	0.55 ± 0.16	0.50 ± 0.13	0.034	0.00078

Notes. EEG, electroencephalogram; REM, rapid eye movement; Cognition +, positive cognitive change; Cognition −, negative cognitive change; SD, standard deviation; W, wake.

p: p-values of ANCOVA including level of education as covariate.

Corrected α-level: Bonferroni–Holm-corrected significance levels.