{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T05:49:16Z","timestamp":1784094556762,"version":"3.55.0"},"reference-count":25,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2022,9,5]],"date-time":"2022-09-05T00:00:00Z","timestamp":1662336000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Physiol."],"abstract":"<jats:p><jats:bold>Background:<\/jats:bold> Effects of prolonged and repeated high-altitude exposure on oxygenation and control of breathing remain uncertain. We hypothesized that prolonged and repeated high-altitude exposure will improve altitude-induced deoxygenation and breathing instability.<\/jats:p><jats:p><jats:bold>Methods:<\/jats:bold> 21 healthy lowlanders, aged 18-30y, underwent two 7-day sojourns at a high-altitude station in Chile (4\u20138\u00a0hrs\/day at 5,050\u00a0m, nights at 2,900\u00a0m), separated by a 1-week recovery period at 520\u00a0m. Respiratory sleep studies recording mean nocturnal pulse oximetry (SpO<jats:sub>2<\/jats:sub>), oxygen desaturation index (ODI, &amp;gt;3% dips in SpO<jats:sub>2<\/jats:sub>), breathing patterns and subjective sleep quality by visual analog scale (SQ-VAS, 0\u2013100% with increasing quality), were evaluated at 520\u00a0m and during nights 1 and 6 at 2,900\u00a0m in the 1st and 2nd altitude sojourn.<\/jats:p><jats:p><jats:bold>Results:<\/jats:bold> At 520\u00a0m, mean \u00b1 SD nocturnal SpO<jats:sub>2<\/jats:sub> was 94 \u00b1 1%, ODI 2.2 \u00b1 1.2\/h, SQ-VAS 59 \u00b1 20%. Corresponding values at 2,900 m, 1st sojourn, night 1 were: SpO<jats:sub>2<\/jats:sub> 86 \u00b1 2%, ODI 23.4 \u00b1 22.8\/h, SQ-VAS 39 \u00b1 23%; 1st sojourn, night 6: SpO<jats:sub>2<\/jats:sub> 90 \u00b1 1%, ODI 7.3 \u00b1 4.4\/h, SQ-VAS 55 \u00b1 20% (<jats:italic>p<\/jats:italic> &amp;lt; 0.05, all differences within corresponding variables). Mean differences (\u0394, 95%CI) in acute effects (2,900 m, night 1, vs 520\u00a0m) between 2nd vs 1st altitude sojourn were: \u0394SpO<jats:sub>2<\/jats:sub> 0% (-1 to 1), \u0394ODI -9.2\/h (-18.0 to -0.5), \u0394SQ-VAS 10% (-6 to 27); differences in acclimatization (changes night 6 vs 1), between 2nd vs 1st sojourn at 2,900\u00a0m were: \u0394SpO<jats:sub>2<\/jats:sub> -1% (-2 to 0), \u0394ODI 11.1\/h (2.5 to 19.7), \u0394SQ-VAS -15% (-31 to 1).<\/jats:p><jats:p><jats:bold>Conclusion:<\/jats:bold> Acute high-altitude exposure induced nocturnal hypoxemia, cyclic deoxygenations and impaired sleep quality. Acclimatization mitigated these effects. After recovery at 520\u00a0m, repeated exposure diminished high-altitude-induced deoxygenation and breathing instability, suggesting some retention of adaptation induced by the first altitude sojourn while subjective sleep quality remained similarly impaired.<\/jats:p>","DOI":"10.3389\/fphys.2022.965021","type":"journal-article","created":{"date-parts":[[2022,9,5]],"date-time":"2022-09-05T05:19:33Z","timestamp":1662355173000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":20,"title":["Acute high altitude exposure, acclimatization and re-exposure on nocturnal breathing"],"prefix":"10.3389","volume":"13","author":[{"given":"Michael","family":"Furian","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Konstantinos","family":"Bitos","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sara E.","family":"Hartmann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lara","family":"Muralt","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mona","family":"Lichtblau","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrick R.","family":"Bader","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jean M.","family":"Rawling","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Silvia","family":"Ulrich","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marc J.","family":"Poulin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Konrad E.","family":"Bloch","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2022,9,5]]},"reference":[{"key":"B1","doi-asserted-by":"crossref","first-page":"667","DOI":"10.1093\/sleep\/22.5.667","article-title":"Sleep-related breathing disorders in adults: Recommendations for syndrome definition and measurement techniques in clinical research. 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