The Psychophysiological Effect of Simulated and Terrestrial Altitude (Hypoxia)

The aim of this study is to compare the psychophysiological effects of terrestrial altitude with a normobaric, hypoxic situation.

Study Overview

• Status: Completed
• Conditions: Hypoxia; Altitude Sickness; Mountain Sickness; Hypoxia, Altitude; Altitude Hypoxia; Altitude
• Intervention / Treatment: Behavioral: Cloud 9; Behavioral: Terrestrial altitude

Detailed Description

Research has consistently shown that exposure to extreme environments (such as high altitude stays) may affect cognitive function. For logistical reasons and to control the experimental set-ups, most of these examinations are carried out in the laboratory. By testing under such controlled conditions, researchers can remove any co-foundational factors and isolate the cause of stress, thereby better understanding the mechanisms by which impairment can occur. However, when people are exposed to such environments in the "real world" (such as altitude), they often experience a number of other additional stressors at the same time, which can also affect their performance. Surprisingly, however, little attention has been paid to the study of these additional stressors in combination.

Although the oxygen content remains constant at various altitudes (20.93%), the air pressure decreases exponentially as the altitude increases. As a result, the oxygen partial pressure in arterial blood and tissue is reduced (hypoxia), leading to a deterioration in both physical and cognitive performance. Hypoxic conditions also alter the perception of pain, which may be particularly relevant for patients suffering from hypoxic conditions. According to the authors' knowledge, there is limited literature investigating and comparing simulated and real psychophysiological responses.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Landquart, Switzerland, 7302
    • Fachhochschule Südschweiz
  • Kanton Graubünden
    • Landquart, Kanton Graubünden, Switzerland, 7302
      • Fachhochschule Südschweiz
    • Landquart, Kanton Graubünden, Switzerland, 7302
      • University of Applied Sciences and Arts of Southern Switzerland (SUPSI)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Healthy, adults aged 18 to 50 years
• No cardiovascular disease and / or surgery
• no surgery on the cardiovascular system.
• No current injuries and / or pain
• Regular and adequate sleep
• No terrestrial altitude of 1000 m exceeded last month (including flights)
• No form of hypoxia exposed last month

Exclusion Criteria:

• Age over 50 years
• current injuries of any kind and / or pain
• Acute and / or chronic pain conditions Known general diseases (e.g., diabetes mellitus)
• fear of hypoxia
• fear of heights or sensitivity to terrestrial altitude
• Regular use of medicines (also bought by yourself), except for contraceptives
• Cardiovascular diseases or abnormalities
• Anomalies of the blood analysis or ECG
• Psychological disorders
• pregnancy / lactation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Simulated altitude; The participants are exposed to simulated altitude in a normobaric situation.	Behavioral: Cloud 9; Cloud 9 is a solid, certified product that complies with European Directives on Electromagnetic Compatibility, Machine Directive, Air Pressure Equipment and Low Voltage Equipment (89/336 / EEC, 91/368 / CEE, 93/68 / CEE, 97/23 / EC, EN61010-1 All directives are in writing in the Supplements to this Ethics Application. Simulated height: The subjects are in the laboratory of our institution and are connected to the Cloud 9 by means of a mask. Subjects are exposed to a simulated altitude of 3530m under normobaric conditions. By means of this intervention the psychophysiological effect under normobaric and hypoxic conditions is determined.
Experimental: Terrestrial altitude; The participants are exposed to terrestrial altitude in a hypobaric situation.	Behavioral: Terrestrial altitude; Terrestrial altitude: The volunteers are in an SAC hut at an altitude of 3000 m. By means of this exposure the psychophysiological effect under hypobaric and hypoxic conditions is determined. The subjects spend the night in this SAC hut and the measurements are repeated the next day.
No Intervention: Control; the participants are exposed to a normoxic and normobaric environment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Oxygenation of the Brain	Brain oxygen saturation is measured non-invasively using a deep tissue oxygenation monitor (moorVMS-NIRS, moor instruments, www.moor.co.uk). For this purpose, adhesive electrodes are applied over the muscle and the forehead. This measurement is taken during the baseline measurements, and during the cognitive performance test. This outcome measure reports the change from baseline for the oxygenation of the brain.	Baseline (participants seated for 15 minutes) and during the cognitive performance under normobaric hypoxia, hypobaric hypoxia, and control conditions (mean over time)
Oxygenation of the Blood	The oxygen saturation of the blood (SpO2) is measured with a portable pulse oximeter with finger clip probe (Nonin 7500, Nonin medical B.V., Plymouth, USA). This measurement is taken during the baseline measurements and after the step-up task. This outcome measure reports the change from baseline for the oxygenation of the blood.	Continuously during the 15-minute seated baseline period before each trial (mean over 15min) and at the end of the step-up test (point measurement)
Mean Arterial Pressure	Blood pressure was measured using an automated sphygmomanometer monitor from the left brachial artery. MAP was calculated using the following formula: MAP = diastolic blood pressure + (systolic blood pressure-diastolic blood pressure) / 3.	At the end of the 15-minute baseline seated period before each trial and at the end of the 3-minute submaximal step-test (Point measurements)
Heart Rate	The heart rate is measured using a pulse belt and an additional 2-point ECG (Actiheart, Camntech Ltd., Cambridge, UK). This measurement is taken during the baseline measurements and after the step-up task. This outcome measure reports the change from baseline for the heart rate.	at baseline and the end of the submaximal step test (point measurements)
Concentration of Blood Lactate	Lactate measurements are performed by capillary blood measurement. This measurement is taken during the baseline measurements and after the step-up task.	at the end of 15min baseline period and the end of the step-up test (point measurements)
Sleep Quality	Sleep quality of the night before the experimental day was assessed using the validated and reliable GSQS, consisting of a 16-item true or false questionnaire. GSQS scores ranged from 0 to 16 whereas higher scores indicated lower subjective sleep quality.	Before the cognitive performance test (point measurement)
Altitude Sickness	Altitude sickness is measured with "Lake Louis acute mountain sickness scale", choosing the most appropriate answer from 5 questions. Questions range from 0 (=no symptoms) to 4 (=severe symptoms). LLAMS symptoms were assessed at the end of each experimental measurement.	After performing the 3-min step-test (point measurment)
Concentration of Salivary Cortisol	Salivary cortisol was assessed from the n = 10 female participants to assess the daily stress level after each experimental day. Through a straw, 3mL of saliva was collected and stored in a refrigerator until the analyses were performed the next day using the enzyme-linked immunosorbent assay (ELISA) method.	After each experimental day, in the evening between 8:30 PM and midnight, measured once before participants went to bed (point measurment)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Thermal comfort and sensation	These parameters are measured by a thermal comfort scale (ranging from 0 [comfortable] to +4 [very uncomfortable]) and a thermal sensation scale (ranging from -4 [ver cold] to +4 [very hot]). These measurements are performed after the baseline measurement and after the cold water bath immersion of the hand and report the change from baseline.	30 minutes

Collaborators and Investigators

• Sponsor: University of Applied Sciences and Arts of Southern Switzerland
• Collaborators: Vrije Universiteit Brussel; University of Portsmouth
• Investigators: Principal Investigator: Ron Clijsen, PhD, University of Applied Sciences and Arts of Southern Switzerland (SUPSI)

Publications and helpful links

General Publications

• Hohenauer E, Freitag L, Costello JT, Williams TB, Kung T, Taube W, Herten M, Clijsen R. The effects of normobaric and hypobaric hypoxia on cognitive performance and physiological responses: A crossover study. PLoS One. 2022 Nov 10;17(11):e0277364. doi: 10.1371/journal.pone.0277364. eCollection 2022.

Helpful Links

• fullversion of publication

Study record dates

Study Major Dates

• Study Start (Actual): June 24, 2019
• Primary Completion (Actual): March 31, 2021
• Study Completion (Actual): April 30, 2022

Study Registration Dates

• First Submitted: August 7, 2019
• First Submitted That Met QC Criteria: August 29, 2019
• First Posted (Actual): August 30, 2019

Study Record Updates

• Last Update Posted (Actual): February 19, 2026
• Last Update Submitted That Met QC Criteria: January 30, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: altitude; cognition; hypoxia; physiology
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Respiration Disorders; Signs and Symptoms, Respiratory; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Hypoxia; Altitude Sickness
• Other Study ID Numbers: 2019-00504

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No