Apnea-induced changes in time estimation and its relation to bradycardia.

Introduction: Both exercise and hypoxia affect human ability to estimate time, an alteration thought to be induced by changes in subjects' level of arousal. Apnea induces cardiovascular changes and a decrease in oxygen uptake that indicate changes in physiological arousal. We tested time estimation (TE) during brief periods of voluntary apnea.

An anxiety, personality and altitude symptomatology study during a 31-day period of hypoxia in a hypobaric chamber (experiment 'Everest-Comex 1997').

Extreme environmental situations are useful tools for the investigation of the general processes of adaptation. Among such situations, high altitude of more than 3000 m produces a set of pathological disorders that includes both cerebral (cAS) and respiratory (RAS) altitude symptoms. High altitude exposure further induces anxiety responses and behavioural disturbances.

Effects of different stay durations on attentional performance during two mountain expeditions.

Background: Hypoxia-induced deficits in intellectual performance are linked to the altitude level reached, the speed of the ascent and the time spent at high altitude. This study analyzes attentional changes during adaptation to two different types of stay at high altitude on two different expeditions: one involving a 16-d trip between 2,000 m and 5,600 m, followed by a 2-d ascent to 6,440 m and back again; the other, a 21-d stay at 6,542 m. We tested the hypothesis that, at similar high altitudes, decrements in attentional performance would only occur during a long duration stay.

Criteria for psychological adaptation to high-altitude hypoxia.

The purpose of this study was to test an ascent program for ideal psychological adaptation to high altitudes. A psychological approach was used to test a model describing a gradual step-by-step ascent. Seven subjects spent nine days between 3,500 m and 4,400 m altitude, followed by eight days climbing 500 m each day from 3,500 m to 5,400 m.

Psychological changes during altitude hypoxia.

We examined the effects of altitude hypoxia on the subject's cognitive functions and psychological state. Two assessment approaches were used, a cognitive-motor task and a structured interview. An experimental group of six subjects was tested three times: once under conditions of normoxia, once 8-20 h after a rapid climb to an altitude of 4383 m, and once 48-60 h after ascent to that altitude.