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Guo C, Lan L, Yan Y, Kang M. Effects of acute exposure to hypoxia on sleep structure in healthy adults: A systematic review. Sleep Med Rev 2024; 75:101928. [PMID: 38614049 DOI: 10.1016/j.smrv.2024.101928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/14/2024] [Accepted: 03/21/2024] [Indexed: 04/15/2024]
Abstract
The sleep quality of lowlanders in hypoxic environments has become increasingly important with an increase in highland and alpine activities. This study aimed to identify the effects of acute exposure to hypoxia on the sleep structure of lowlanders and to analyze the changes in sleep indicators at varying levels of hypoxia. This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Twenty-three studies were screened and included in the quantitative analysis. The results showed that acute exposure to hypoxia reduced sleep quality in lowlanders. Post-sleep arousal events and the percentage of N1 were significantly increased, whereas total sleep time, sleep efficiency, and the percentage of N3 and rapid eye movement sleep were significantly decreased in hypoxic environments. Acute exposure to hypoxia had the greatest negative impact on wakefulness after sleep onset (WASO). In addition, a larger decrease in sleep efficiency and higher increase in the percentages of N1 and WASO were observed when lowlanders were exposed to higher levels of hypoxia. This study clarifies the quantitative effects of acute hypoxic exposure on sleep in lowlanders based on original studies and explains the sleep disorders faced by lowlanders in hypoxic environments.
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Affiliation(s)
- Chao Guo
- Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, China
| | - Li Lan
- Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, China.
| | - Yan Yan
- Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, China
| | - Mengyuan Kang
- Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, China
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Ibrahim A, Stefani A, Cesari M, Roche J, Gatterer H, Holzknecht E, Turner R, Vinetti G, Furian M, Heidbreder A, Högl B, Siebenmann C. Effects of periodic breathing on sleep at high altitude: a randomized, placebo-controlled, crossover study using inspiratory CO 2. J Physiol 2024. [PMID: 38408065 DOI: 10.1113/jp285397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 01/17/2024] [Indexed: 02/28/2024] Open
Abstract
Hypoxia at high altitude facilitates changes in ventilatory control that can lead to nocturnal periodic breathing (nPB). Here, we introduce a placebo-controlled approach to prevent nPB by increasing inspiratory CO2 and used it to assess whether nPB contributes to the adverse effects of hypoxia on sleep architecture. In a randomized, single-blinded, crossover design, 12 men underwent two sojourns (three days/nights each, separated by 4 weeks) in hypobaric hypoxia corresponding to 4000 m altitude, with polysomnography during the first and third night of each sojourn. During all nights, subjects' heads were encompassed by a canopy retaining exhaled CO2 , and CO2 concentration in the canopy (i.e. inspiratory CO2 concentration) was controlled by adjustment of fresh air inflow. Throughout the placebo sojourn inspiratory CO2 was ≤0.2%, whereas throughout the other sojourn it was increased to 1.76% (IQR, 1.07%-2.44%). During the placebo sojourn, total sleep time (TST) with nPB was 54.3% (37.4%-80.8%) and 45.0% (24.5%-56.5%) during the first and the third night, respectively (P = 0.042). Increased inspiratory CO2 reduced TST with nPB by an absolute 38.1% (28.1%-48.1%), the apnoea-hypopnoea index by 58.1/h (40.1-76.1/h), and oxygen desaturation index ≥3% by 56.0/h (38.9.1-73.2/h) (all P < 0.001), whereas it increased the mean arterial oxygen saturation in TST by 2.0% (0.4%-3.5%, P = 0.035). Increased inspiratory CO2 slightly increased the percentage of N3 sleep during the third night (P = 0.045), without other effects on sleep architecture. Increasing inspiratory CO2 effectively prevented hypoxia-induced nPB without affecting sleep macro-architecture, indicating that nPB does not explain the sleep deterioration commonly observed at high altitudes. KEY POINTS: Periodic breathing is common during sleep at high altitude, and it is unclear how this affects sleep architecture. We developed a placebo-controlled approach to prevent nocturnal periodic breathing (nPB) with inspiratory CO2 administration and used it to assess the effects of nPB on sleep in hypobaric hypoxia. Nocturnal periodic breathing was effectively mitigated by an increased inspiratory CO2 fraction in a blinded manner. Prevention of nPB did not lead to relevant changes in sleep architecture in hypobaric hypoxia. We conclude that nPB does not explain the deterioration in sleep architecture commonly observed at high altitude.
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Affiliation(s)
- Abubaker Ibrahim
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Ambra Stefani
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Matteo Cesari
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Johanna Roche
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Evi Holzknecht
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Rachel Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Giovanni Vinetti
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Michael Furian
- Department of Respiratory Medicine, University Hospital of Zurich, Zurich, Switzerland
| | - Anna Heidbreder
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Birgit Högl
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
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Rojas-Córdova S, Torres-Fraga MG, Rodríguez-Reyes YG, Guerrero-Zúñiga S, Vázquez-García JC, Carrillo-Alduenda JL. Altitude and Breathing during Sleep in Healthy Persons and Sleep Disordered Patients: A Systematic Review. Sleep Sci 2023; 16:117-126. [PMID: 37151770 PMCID: PMC10157825 DOI: 10.1055/s-0043-1767745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 06/28/2022] [Indexed: 05/09/2023] Open
Abstract
Objetive The aim of this systematic review is to analyze the recent scientific evidence of the clinical effects of altitude on breathing during sleep in healthy persons and sleep disordered patients. Material and Methods A search was carried out in PubMed and Scopus looking for articles published between January 1, 2010 and December 31, 2021, in English and Spanish, with the following search terms: "sleep disorders breathing and altitude". Investigations in adults and carried out at an altitude of 2000 meters above mean sea level (MAMSL) or higher were included. The correlation between altitude, apnea hypopnea index (AHI) and mean SpO2 during sleep was calculated. Results 18 articles of the 112 identified were included. A good correlation was found between altitude and AHI (Rs = 0.66 P = 0.001), at the expense of an increase in the central apnea index. Altitude is inversely proportional to oxygenation during sleep (Rs = -0.93 P = 0.001), and an increase in the desaturation index was observed (3% and 4%). On the treatment of respiratory disorders of sleeping at altitude, oxygen is better than servoventilation to correct oxygenation during sleep in healthy subjects and acetazolamide controlled respiratory events and oxygenation during sleep in patients with obstructive sleep apnea under treatment with CPAP. Conclusions Altitude increases AHI and decreases oxygenation during sleep; oxygen and acetazolamide could be an effective treatment for sleep-disordered breathing at altitude above 2000 MAMSL.
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Affiliation(s)
| | | | | | - Selene Guerrero-Zúñiga
- National Institute of Respiratory Diseases, Sleep Medicine Unit, Mexico City, Mexico City, Mexico
| | | | - José Luis Carrillo-Alduenda
- National Institute of Respiratory Diseases, Sleep Medicine Unit, Mexico City, Mexico City, Mexico
- Address for correspondence José Luis Carrillo-Alduenda
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Pramsohler S, Wimmer S, Kopp M, Gatterer H, Faulhaber M, Burtscher M, Netzer NC. Normobaric hypoxia overnight impairs cognitive reaction time. BMC Neurosci 2017; 18:43. [PMID: 28506292 PMCID: PMC5433012 DOI: 10.1186/s12868-017-0362-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 05/10/2017] [Indexed: 01/04/2023] Open
Abstract
Background Impaired reaction time in patients suffering from hypoxia during sleep, caused by sleep breathing disorders, is a well-described phenomenon. High altitude sleep is known to induce periodic breathing with central apneas and oxygen desaturations, even in perfectly healthy subjects. However, deficits in reaction time in mountaineers or workers after just some nights of hypoxia exposure are not sufficiently explored. Therefore, we aimed to investigate the impact of sleep in a normobaric hypoxic environment on reaction time divided by its cognitive and motoric components. Eleven healthy non acclimatized students (5f, 6m, 21 ± 2.1 years) slept one night at a simulated altitude of 3500 m in a normobaric hypoxic room, followed by a night with polysomnography at simulated 5500 m. Preexisting sleep disorders were excluded via BERLIN questionnaire. All subjects performed a choice reaction test (SCHUHFRIED RT, S3) at 450 m and directly after the nights at simulated 3500 and 5500 m. Results We found a significant increase of cognitive reaction time with higher altitude (p = 0.026). No changes were detected in movement time (p = n.s.). Reaction time, the combined parameter of cognitive- and motoric reaction time, didn’t change either (p = n.s.). Lower SpO2 surprisingly correlated significantly with shorter cognitive reaction time (r = 0.78, p = 0.004). Sleep stage distribution and arousals at 5500 m didn’t correlate with reaction time, cognitive reaction time or movement time. Conclusion Sleep in hypoxia does not seem to affect reaction time to simple tasks. The component of cognitive reaction time is increasingly delayed whereas motoric reaction time seems not to be affected. Low SpO2 and arousals are not related to increased cognitive reaction time therefore the causality remains unclear. The fact of increased cognitive reaction time after sleep in hypoxia, considering high altitude workers and mountaineering operations with overnight stays, should be further investigated.
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Affiliation(s)
- Stephan Pramsohler
- Hermann Buhl Institute for Hypoxia and Sleep Medicine Research, Ghersburgstr. 9, 83043, Bad Aibling, Germany.
| | - Stefan Wimmer
- Hermann Buhl Institute for Hypoxia and Sleep Medicine Research, Ghersburgstr. 9, 83043, Bad Aibling, Germany.,Department of Sport Science, University Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Martin Kopp
- Department of Sport Science, University Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Hannes Gatterer
- Department of Sport Science, University Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Martin Faulhaber
- Department of Sport Science, University Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Martin Burtscher
- Department of Sport Science, University Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Nikolaus Cristoph Netzer
- Hermann Buhl Institute for Hypoxia and Sleep Medicine Research, Ghersburgstr. 9, 83043, Bad Aibling, Germany.,Department of Sport Science, University Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria.,Division of Sports Medicine and Rehabilitation, Department of Medicine, University Ulm, Fürstenweg 185, Ulm, Germany
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