Abnormal daytime sleepiness in dementia with Lewy bodies compared to Alzheimer’s disease using the Multiple Sleep Latency Test

Table 2 Overnight polysomnography in the dementia with Lewy bodies and Alzheimer’s disease dementia groups ^a

	DLB	AD dementia	F/χ²	P-value
No. of participants	61	26
Time in bed, min	488 ± 78	560 ± 65	17	<0.01
Total sleep time, min	348 ± 99	382 ± 77	2.43	0.12
Sleep efficiency, %	72 ± 18	69 ± 17	0.24	0.63
Initial sleep latency, min	27 ± 38	23 ± 20	0.26	0.61
Initial REM sleep latency, min	144 ± 101	140 ± 105	0.03	0.87
Stage N1, % total sleep time	12 ± 11	16 ± 12	1.9	0.17
Stage N2, % total sleep time	53 ± 16	53 ± 13	0.005	0.99
Stage N3, % total sleep time	22 ± 16	14 ± 9	5.6	0.02
Stage REM, % total sleep time	14 ± 12	17 ± 8	1.7	0.19
Arousal index/hr	25 ± 15	29 ± 17	0.88	0.35
Respiratory disturbance index/hr	10 ± 11	8 ± 12	0.55	0.46
Respiratory disturbance index ≥15, %	18%	15%	0.11	0.74
Movement-related arousals/hr	4.3 ± 7	5.8 ± 6	1.28	0.28
Spontaneous arousals/hr	8.7 ± 8	9.8 ± 8	0.32	0.57
Oxygen saturation, %	94 ± 2	95 ± 2	0.52	0.47
REM sleep without atonia, %	71%	8%	43.4	<0.01
Absence of REM sleep, %	19%	0%	–	–

^aValues represent mean ± standard deviation or percentage per group. Index values/hour reflect the number of arousals per total hours of sleep time. AD dementia, Alzheimer’s disease dementia; DLB, Dementia with Lewy bodies; REM, Rapid eye movement. We used Fisher’s exact test for χ² comparisons with less than five per cell, and no statistical comparisons were made with one or less per cell.