title: Trait-like individual differences in the human sleep electroencephalogram.
abstract: We aimed to examine whether commonly observed individual differences in sleep architecture and the sleep electroencephalogram reflect individual traits, which are amenable to a genetic investigation of human sleep. We studied intra-individual stability and inter-individual variation in sleep and sleep electroencephalogram spectra across four baseline recordings of eight healthy young men. A similarity concept based on Euclidean distances between vectors was applied. Visually scored sleep variables served as feature vector components, along with electroencephalogram power spectra in non-rapid-eye-movement and rapid-eye-movement sleep. The distributions of similarity coefficients of feature vectors revealed a clear distinction between high within-subject similarity (i.e. stability), and low between-subject similarity (i.e. variation). Moreover, a cluster analysis based on electroencephalogram spectra in both non-rapid-eye-movement and rapid-eye-movement sleep segregated all four baseline nights of each individual into a distinct cluster. To investigate whether high and low sleep pressure affects the similarity coefficients, normalized non-rapid-eye-movement sleep electroencephalogram spectra of the first and second half of the recordings were compared. Because the electroencephalogram changes systematically in the course of the night, within-subject variation no longer differed from between-subject variation. In conclusion, our data provide evidence for trait-like characteristics in the sleep electroencephalogram. Further studies may help to identify distinct phenotypes to search for genes underlying functional aspects of undisturbed human sleep.
authors.affiliation: Institute of Pharmacology and Toxicology and Center for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Buckelmüller
authors.forename: H-P
authors.initials: HP
authors.lastname: Landolt
authors.forename: H H
authors.initials: HH
authors.lastname: Stassen
authors.forename: P
authors.initials: P
authors.lastname: Achermann
mesh_terms: D000328:Adult; D016000:Cluster Analysis; D004569:Electroencephalography; D006801:Humans; D007206:Individuality; D008297:Male; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation / Q000503:physiopathology; D012895:Sleep, REM / Q000502:physiology; D014851:Wakefulness