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Effect of Acute, Subacute, and Repeated Exposure to High Altitude (5050 m) on Psychomotor Vigilance


Pun, Matiram; Hartmann, Sara E; Furian, Michael; Dyck, Adrienna M; Muralt, Lara; Lichtblau, Mona; Bader, Patrick R; Rawling, Jean M; Ulrich, Silvia; Bloch, Konrad E; Poulin, Marc J (2018). Effect of Acute, Subacute, and Repeated Exposure to High Altitude (5050 m) on Psychomotor Vigilance. Frontiers in Physiology, 9:677.

Abstract

High altitude (HA) hypoxia may affect cognitive performance and sleep quality. Further, vigilance is reduced following sleep deprivation. We investigated the effect on vigilance, actigraphic sleep indices, and their relationships with acute mountain sickness (AMS) during very HA exposure, acclimatization, and re-exposure. A total of 21 healthy altitude-naive individuals (25 ± 4 years; 13 females) completed 2 cycles of altitude exposure separated by 7 days at low altitude (LA, 520 m). Participants slept at 2900 m and spent the day at HA, (5050 m). We report acute altitude exposure on Day 1 (LA vs. HA1) and after 6 days of acclimatization (HA1 vs. HA6). Vigilance was quantified by reaction speed in the 10-min psychomotor vigilance test reaction speed (PVT-RS). AMS was evaluated using the Environmental Symptoms Questionnaire Cerebral Score (AMS-C score). Nocturnal rest/activity was recorded to estimate sleep duration using actigraphy. In , PVT-RS was slower at HA1 compared to LA (4.1 ± 0.8 vs. 4.5 ± 0.6 s, respectively, = 0.029), but not at HA6 (4.6 ± 0.7; > 0.05). In , PVT-RS at HA1 (4.6 ± 0.7) and HA6 (4.8 ± 0.6) were not different from LA (4.8 ± 0.6, > 0.05) and significantly greater than corresponding values in . In both cycles, AMS scores were higher at HA1 than at LA and HA6 ( < 0.05). Estimated sleep durations (TST) at LA, 1st and 5th nights were 431.3 ± 28.7, 418.1 ± 48.6, and 379.7 ± 51.4 min, respectively, in and they were significantly reduced during acclimatization exposures (LA vs. 1st night, > 0.05; LA vs. 5th night, = 0.012; and 1st vs. 5th night, = 0.054). LA, 1st and 5th nights TST in were 477.5 ± 96.9, 430.9 ± 34, and 341.4 ± 32.2, respectively, and we observed similar deteriorations in TST as in (LA vs. 1st night, > 0.05; LA vs. 5th night, = 0.001; and 1st vs. 5th night, < 0.0001). At HA1, subjects who reported higher AMS-C scores exhibited slower PVT-RS ( = -0.56; < 0.01). Subjects with higher AMS-C scores took longer time to react to the stimuli during acute exposure ( = 0.62, < 0.01) during HA1 of . Acute exposure to HA reduces the PVT-RS. Altitude acclimatization over 6 days recovers the reaction speed and prevents impairments during subsequent altitude re-exposure after 1 week spent near sea level. However, acclimatization does not lead to improvement in total sleep time during acute and subacute exposures.

Abstract

High altitude (HA) hypoxia may affect cognitive performance and sleep quality. Further, vigilance is reduced following sleep deprivation. We investigated the effect on vigilance, actigraphic sleep indices, and their relationships with acute mountain sickness (AMS) during very HA exposure, acclimatization, and re-exposure. A total of 21 healthy altitude-naive individuals (25 ± 4 years; 13 females) completed 2 cycles of altitude exposure separated by 7 days at low altitude (LA, 520 m). Participants slept at 2900 m and spent the day at HA, (5050 m). We report acute altitude exposure on Day 1 (LA vs. HA1) and after 6 days of acclimatization (HA1 vs. HA6). Vigilance was quantified by reaction speed in the 10-min psychomotor vigilance test reaction speed (PVT-RS). AMS was evaluated using the Environmental Symptoms Questionnaire Cerebral Score (AMS-C score). Nocturnal rest/activity was recorded to estimate sleep duration using actigraphy. In , PVT-RS was slower at HA1 compared to LA (4.1 ± 0.8 vs. 4.5 ± 0.6 s, respectively, = 0.029), but not at HA6 (4.6 ± 0.7; > 0.05). In , PVT-RS at HA1 (4.6 ± 0.7) and HA6 (4.8 ± 0.6) were not different from LA (4.8 ± 0.6, > 0.05) and significantly greater than corresponding values in . In both cycles, AMS scores were higher at HA1 than at LA and HA6 ( < 0.05). Estimated sleep durations (TST) at LA, 1st and 5th nights were 431.3 ± 28.7, 418.1 ± 48.6, and 379.7 ± 51.4 min, respectively, in and they were significantly reduced during acclimatization exposures (LA vs. 1st night, > 0.05; LA vs. 5th night, = 0.012; and 1st vs. 5th night, = 0.054). LA, 1st and 5th nights TST in were 477.5 ± 96.9, 430.9 ± 34, and 341.4 ± 32.2, respectively, and we observed similar deteriorations in TST as in (LA vs. 1st night, > 0.05; LA vs. 5th night, = 0.001; and 1st vs. 5th night, < 0.0001). At HA1, subjects who reported higher AMS-C scores exhibited slower PVT-RS ( = -0.56; < 0.01). Subjects with higher AMS-C scores took longer time to react to the stimuli during acute exposure ( = 0.62, < 0.01) during HA1 of . Acute exposure to HA reduces the PVT-RS. Altitude acclimatization over 6 days recovers the reaction speed and prevents impairments during subsequent altitude re-exposure after 1 week spent near sea level. However, acclimatization does not lead to improvement in total sleep time during acute and subacute exposures.

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Pneumology
Dewey Decimal Classification:610 Medicine & health
Scopus Subject Areas:Life Sciences > Physiology
Health Sciences > Physiology (medical)
Language:English
Date:2018
Deposited On:03 Jan 2019 11:11
Last Modified:11 May 2020 18:21
Publisher:Frontiers Research Foundation
ISSN:1664-042X
OA Status:Gold
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.3389/fphys.2018.00677
PubMed ID:29915546

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