title: Altitude insomnia: studies during an expedition to the Himalayas.
abstract: During an expedition to the Himalayas, we studied the sleep and respiration of six climbers. Three ingested acetazolamide (500 mg) daily throughout the climb and the other three ingested placebo. At high altitude (4,150-4,846 m), each subject ingested temazepam (10 mg) for one night and placebo for another. Acetazolamide improved sleep above 2,750 m, but it is uncertain whether this was due to sedation or to improvements in arterial oxygen saturation. Sleep was markedly disturbed in all subjects above 4,000 m. Temazepam improved sleep, and in subjects taking acetazolamide, it reduced sleep-onset latencies and increased sleep efficiency close to that of sea level values. These observations suggest that the prophylactic use of acetazolamide is likely to improve sleep in climbers and that a low dose of a benzodiazepine such as temazepam (10 mg) may be beneficial at high altitude. Studies are now needed to exclude any possibility of respiratory impairment at altitude before a firm recommendation can be made regarding the routine use of this hypnotic.
authors.affiliation: Royal Air Force Institute of Aviation Medicine, Farnborough, Hampshire, England.
authors.forename: A N
authors.initials: AN
authors.lastname: Nicholson
authors.forename: P A
authors.initials: PA
authors.lastname: Smith
authors.forename: B M
authors.initials: BM
authors.lastname: Stone
authors.forename: A R
authors.initials: AR
authors.lastname: Bradwell
authors.forename: J H
authors.initials: JH
authors.lastname: Coote
mesh_terms: D000086:Acetazolamide / Q000008:administration & dosage*; D000328:Adult; D000532:Altitude Sickness / Q000503:physiopathology*; D014151:Anti-Anxiety Agents / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009051:Mountaineering; D009119:Muscle Contraction / Q000187:drug effects; D012119:Respiration / Q000187:drug effects; D007319:Sleep Initiation and Maintenance Disorders / Q000188:drug therapy*; D012894:Sleep Stages / Q000187:drug effects; D013693:Temazepam / Q000008:administration & dosage*
chemical_list: D014151:Anti-Anxiety Agents; D013693:Temazepam; D000086:Acetazolamide