title: Sleep respiratory disturbances and arousals at moderate altitude have overlapping electroencephalogram spectral signatures.
abstract: An ascent to altitude has been shown to result in more central apneas and a shift towards lighter sleep in healthy individuals. This study employs spectral analysis to investigate the impact of respiratory disturbances (central/obstructive apnea and hypopnea or periodic breathing) at moderate altitude on the sleep electroencephalogram (EEG) and to compare EEG changes resulting from respiratory disturbances and arousals. Data were collected from 51 healthy male subjects who spent 1 night at moderate altitude (2590 m). Power density spectra of Stage 2 sleep were calculated in a subset (20) of these participants with sufficient artefact-free data for (a) epochs with respiratory events without an accompanying arousal, (b) epochs containing an arousal and (c) epochs of undisturbed Stage 2 sleep containing neither arousal nor respiratory events. Both arousals and respiratory disturbances resulted in reduced power in the delta, theta and spindle frequency range and increased beta power compared to undisturbed sleep. The similarity of the EEG changes resulting from altitude-induced respiratory disturbances and arousals indicates that central apneas are associated with micro-arousals, not apparent by visual inspection of the EEG. Our findings may have implications for sleep in patients and mountain tourists with central apneas and suggest that respiratory disturbances not accompanied by an arousal may, none the less, impact sleep quality and impair recuperative processes associated with sleep more than previously believed.
authors.affiliation: Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland; Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: Katrin
authors.initials: K
authors.lastname: Stadelmann
authors.forename: Tsogyal D
authors.initials: TD
authors.lastname: Latshang
authors.forename: Leila
authors.initials: L
authors.lastname: Tarokh
authors.forename: Christian M
authors.initials: CM
authors.lastname: Lo Cascio
authors.forename: Noemi
authors.initials: N
authors.lastname: Tesler
authors.forename: Anne-Christin
authors.initials: AC
authors.lastname: Stoewhas
authors.forename: Malcolm
authors.initials: M
authors.lastname: Kohler
authors.forename: Konrad E
authors.initials: KE
authors.lastname: Bloch
authors.forename: Reto
authors.initials: R
authors.lastname: Huber
authors.forename: Peter
authors.initials: P
authors.lastname: Achermann
mesh_terms: D000328:Adult; D000531:Altitude; D001143:Arousal; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D012119:Respiration; D012890:Sleep; D020182:Sleep Apnea, Central / Q000503:physiopathology*; D012894:Sleep Stages
keywords: apnea; hypoxia; sleep EEG; spectral analysis