Prospective interventional trial in lowlanders evaluating the effect of acute exposure, acclimatization and re-exposure to high altitude on psychomotor vigilance to measure sustained attention.

Baseline measurements will be performed in Santiago de Chile, 520 m, over the course of 3 days. Participants will then travel by commercial airline (2 h flight) and by bus (2 h ride) to the ALMA base camp located at 2900 m near San Pedro de Atacama, northern Chile. Participants will stay there for the next 7 nights and they will spend the days (6 total; 6-8 h daily) at the telescope station at 5050 m while undergoing testing as described above at the first and the last day at 5050m. Daily transports from 2900 to 5050 m will be by car (1 h ride, one way). After the first 7 day altitude sojourn participants will return to the Santiago area (520 m) for a 7 day recovery period. A second altitude sojourn with an identical schedule as the one described above and a final low altitude stay of 3 days will follow.

Inclusion Criteria:

• born, raised and currently living <1300m
• No overnight stays at altitudes >1500m 4 weeks before the study

Exclusion Criteria:

• previous altitude intolerance <3000m
• pregnancy
• health impairment, which requires regular treatment