title: High altitude sleep disturbances monitored by actigraphy and polysomnography.
abstract: OBJECTIVE
  Data on sleep at altitude are scant due to the limited availability of polysomnography. Therefore, we investigated whether actigraphy might serve as a simple tool for monitoring sleep during altitude field studies.
  
  
  METHODS
  Fourteen mountaineers participating in studies on dexamethasone prophylaxis of high altitude pulmonary edema were monitored by actigraphy and polysomnography during 1 night at Zurich (490 m) and 4 nights at the Regina Margherita hut (4559 m). Total sleep time (TST) estimated by actigraphy was compared to polysomnography and subjective sleep quality.
  
  
  RESULTS
  In 64 comparisons, mean differences±2SD (bias±limits of agreement) between actigraphy and polysomnography were 5±35 min for TST and 1±7% for sleep efficiency. Correlations between subjective and polysomnographic estimates of sleep efficiency and sleep latency were nonsignificant. Medians of nocturnal oxygen saturation were 96% at 490 m and 74%-81% during nights 1 to 4 at 4459 m (p<0.05 vs. 490 m). Medians of polysomnographic TST were similar at 490 m (451 min) and 4559 m (377-456 min during nights 1 to 4, p=NS) but the proportions of slow wave and REM sleep were reduced and arousals were more common (p<0.05 all instances).
  
  
  CONCLUSIONS
  Actigraphy accurately estimates sleep efficiency and duration. Due to its portability and simple use and the potential application over several weeks, it is a convenient tool for investigating altitude effects on sleep during field studies.
authors.affiliation: Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Nussbaumer-Ochsner
authors.forename: Nicole
authors.initials: N
authors.lastname: Schuepfer
authors.forename: Christoph
authors.initials: C
authors.lastname: Siebenmann
authors.forename: Marco
authors.initials: M
authors.lastname: Maggiorini
authors.forename: Konrad E
authors.initials: KE
authors.lastname: Bloch
mesh_terms: D056044:Actigraphy; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000150:complications / Q000503:physiopathology*; D000704:Analysis of Variance; D001274:Atmospheric Pressure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D012893:Sleep Wake Disorders / Q000209:etiology / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D010100:Oxygen