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Are nocturnal breathing, sleep, and cognitive performance impaired at moderate altitude (1,630-2,590 m)?

ABSTRACT: Newcomers at high altitude (> 3,000 m) experience periodic breathing, sleep disturbances, and impaired cognitive performance. Whether similar adverse effects occur at lower elevations is uncertain, although numerous lowlanders travel to moderate altitude for professional or recreational activities. We evaluated the hypothesis that nocturnal breathing, sleep, and cognitive performance of lowlanders are impaired at moderate altitude.Randomized crossover trial.University hospital at 490 m, Swiss mountain villages at 1,630 m and 2,590 m.Fifty-one healthy men, median (quartiles) age 24 y (20-28 y), living below 800 m.Studies at Zurich (490 m) and during 4 consecutive days at 1,630 m and 2,590 m, respectively, 2 days each. The order of altitude exposure was randomized. Polysomnography, psychomotor vigilance tests (PVT), the number back test, several other tests of cognitive performance, and questionnaires were evaluated.The median (quartiles) apnea-hypopnea index at 490 m was 4.6/h (2.3; 7.9), values at 1,630 and 2,590 m, day 1 and 2, respectively, were 7.0/h (4.1; 12.6), 5.4/h (3.5; 10.5), 13.1/h (6.7; 32.1), and 8.0/h (4.4; 23.1); corresponding values of mean nocturnal oxygen saturation were 96% (95; 96), 94% (93; 95), 94% (93; 95), 90% (89; 91), 91% (90; 92), P < 0.05 versus 490 m, all instances. Slow wave sleep on the first night at 2,590 m was 21% (18; 25) versus 24% (20; 27) at 490 m (P < 0.05). Psychomotor vigilance and various other measures of cognitive performance did not change significantly.Healthy men acutely exposed during 4 days to hypoxemia at 1,630 m and 2,590 m reveal a considerable amount of periodic breathing and sleep disturbances. However, no significant effects on psychomotor reaction speed or cognitive performance were observed.Clinicaltrials.gov: NCT01130948.

SUBMITTER: Latshang TD

PROVIDER: S-EPMC3825448 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Are nocturnal breathing, sleep, and cognitive performance impaired at moderate altitude (1,630-2,590 m)?

Latshang Tsogyal D TD Lo Cascio Christian M CM Stöwhas Anne-Christin AC Grimm Mirjam M Stadelmann Katrin K Tesler Noemi N Achermann Peter P Huber Reto R Kohler Malcolm M Bloch Konrad E KE

Sleep 20131201 12

<h4>Study objectives</h4>Newcomers at high altitude (> 3,000 m) experience periodic breathing, sleep disturbances, and impaired cognitive performance. Whether similar adverse effects occur at lower elevations is uncertain, although numerous lowlanders travel to moderate altitude for professional or recreational activities. We evaluated the hypothesis that nocturnal breathing, sleep, and cognitive performance of lowlanders are impaired at moderate altitude.<h4>Design</h4>Randomized crossover tria ...[more]

PMID: 24293773

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Project description:Purpose: Nitric oxide (NO) bioavailability is reduced during acute altitude exposure, contributing toward the decline in physiological and cognitive function in this environment. This study evaluated the effects of nitrate ([Formula: see text]) supplementation on NO bioavailability, physiological and cognitive function, and exercise performance at moderate and very-high simulated altitude. Methods:Ten males (mean (SD): [Formula: see text]: 60.9 (10.1) ml·kg-1·min-1) rested and performed exercise twice at moderate (~14.0% O2; ~3,000 m) and twice at very-high (~11.7% O2; ~4,300 m) simulated altitude. Participants ingested either 140 ml concentrated [Formula: see text]-rich (BRJ; ~12.5 mmol [Formula: see text]) or [Formula: see text]-deplete (PLA; 0.01 mmol [Formula: see text]) beetroot juice 2 h before each trial. Participants rested for 45 min in normobaric hypoxia prior to completing an exercise task. Exercise comprised a 45 min walk at 30% [Formula: see text] and a 3 km time-trial (TT), both conducted on a treadmill at a 10% gradient whilst carrying a 10 kg backpack to simulate altitude hiking. Plasma nitrite concentration ([[Formula: see text]]), peripheral oxygen saturation (SpO2), pulmonary oxygen uptake ([Formula: see text]), muscle and cerebral oxygenation, and cognitive function were measured throughout. Results: Pre-exercise plasma [[Formula: see text]] was significantly elevated in BRJ compared with PLA (p = 0.001). Pulmonary [Formula: see text] was reduced (p = 0.020), and SpO2 was elevated (p = 0.005) during steady-state exercise in BRJ compared with PLA, with similar effects at both altitudes. BRJ supplementation enhanced 3 km TT performance relative to PLA by 3.8% [1,653.9 (261.3) vs. 1718.7 (213.0) s] and 4.2% [1,809.8 (262.0) vs. 1,889.1 (203.9) s] at 3,000 and 4,300 m, respectively (p = 0.019). Oxygenation of the gastrocnemius was elevated during the TT consequent to BRJ (p = 0.011). The number of false alarms during the Rapid Visual Information Processing Task tended to be lower with BRJ compared with PLA prior to altitude exposure (p = 0.056). Performance in all other cognitive tasks did not differ significantly between BRJ and PLA at any measurement point (p ? 0.141). Conclusion: This study suggests that BRJ improves physiological function and exercise performance, but not cognitive function, at simulated moderate and very-high altitude.

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Are nocturnal breathing, sleep, and cognitive performance impaired at moderate altitude (1,630-2,590 m)?

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Are nocturnal breathing, sleep, and cognitive performance impaired at moderate altitude (1,630-2,590 m)?

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