Comparison of a frequency-based analysis of electroencephalograms (Z-ratio) and visual scoring on the multiple sleep latency test.
In a sample of multiple sleep latency test naps following nocturnal polysomnograms from a group of 13 patients of varying ages and diagnoses, we compared a computer-derived electroencephalographic (EEG) measure (z-ratio) with standard visual sleep stage scoring. In this clinical population, z-ratio scoring agreed with human scorers approximately 80% of the time when determining sleep versus wake in 30-second epochs. These results show that a single, objectively quantifiable value derived from a single channel of EEG can distinguish between sleep and wakefulness (as defined by Rechtschaffen and Kales) with at least a moderate degree of precision. When refined, the z-ratio method might be of use as the basis for a new sleep scoring system, particularly where an accurate determination of sleep onset is required.
Albertario
C L
CL
Winthrop-University Hospital Sleep Disorders Center, Mineola, New York 11501, USA.
Zendell
S M
SM
Hertz
G
G
Maberino
M M
MM
Feinsilver
S H
SH
D000293:Adolescent; D000328:Adult; D000368:Aged; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012895:Sleep, REM; D012984:Software; D014851:Wakefulness